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HomeMy WebLinkAboutManushin Volcano Geothermal Resources 1982MAKUSHIN VOLCANO GEOTHERMAL RESOURCES Informal Report / submitted to the Alaska Power Authority by:}.' John W.Reeder,Ph.D. Clay Nichols,Ph.D. Roman Motyka Mitch Henning State of Alaska Departmentof Natural Resources Division of Geological &Geophysical Surveys November 30,1982 Proj.Code: rile Cod:32 O70! J.Date:22.234.2 Informal DGGS Makushin Volcano Geothermal Report,November 30,1982 I.Introduction II.General geology and geothermal resource review (Reeder) ITI.Detailed geologic observations including structural and gravity data, models,and interpretations (Reeder) /IV.Petrographic geochemical analyses of rocks (Reeder and Nichols) Preliminary petrographic evaluation,geochemical evaluation, potassium-argon age dating,alteration and clay mineralogy evaluation V.Volcanic hazard considerations (Reeder) VI.Geothermal-fluid chemical considerations (Motyka) VII.Conclusions including general drilling target recommendations (Reeder and Nichols) References Appendix A,Figures Appendix B,Tables Appendix C,Letters Appendix D,Plates I,Introduction The purpose of this report is to summarize the studies performed by DGGS during the 1982 field season in the vicinity of Makushin Volcano,Unalaska to the Alaska Power Authority.These studies included:geologic mapping, geochemical sampling of geothermal fluids,detailed structural and gravity investigations,petrographic and geochemical rock investigations including K-Ar age dating and clay mineralogy determinations,and initial volcanic hazard considerations.A preliminary drilling-target recommendation section has also been included as representing the summary and the general APA purpose of this report./ II.General Geology and Geothermal Resource Review Fumaroles occurring in the Makushin Volcano region of Unalaska Island,many being discovered in 1980 and described for the first time by Reeder (1981 and 1982),are direct evidence of vapor-dominated hydrothermal systems.The term "vapor-dominated hydrothermal systems"was originally coined by White and others (1971)for those systems in which the reservoir fluids are mainly vapor,not liquid;i.e.,wet,dry-saturated,or superheated steam.There are only a few places in the world,such as The Geysers,California,and Larderello,Italy, where hydrothermal systems consist mainly of vapor.These systems have been developed where they now represent the major source of electrical geothermal power.The "vapor-dominated"hydrothermal systems in the Makushin Volcano region probably consist of wet steam., Some warm and hot springs were found near the fumarole fields at lower elevations (Reeder,1982).Initial water analyses of some of these hot and warm springs (Motyka and others,1981)indicated near-neutral sodium-bicarbonate- sulfate waters similar to hydrothermal waters described.by Mahon and others (1980),which consisted predominantly of meteoric waters that had been heated by vapor-dominated hydrothermal systems generated from greater than 150°C alkali- chloride waters at greater depth.The hot springs in the Makushin Volcano region probably derive most of their heat from the vapor-dominated hydrothermal systems that are the source of the fumaroles throughout the region.In some cases,this type cf relationship between surface waters and hot spriigs can be seen directly in the field. The rocks of Unalaska Island include an older group of altered sedimentary and volcanic rocks designated the Unalaska Formation by Drewes and others (1961),a group of intermediate-age plutonic rocks,and a younger group of unaltered volcanic rocks.The three groups can be correlated with those found throughout the eastern and central Aleutian Islands,namely,an early series of a marine volcanic and sedimentary sequence that has been matamorphosed to a greenschist grade,a middle series of plutonic rocks,and a late series of an unaltered sequence of Tertiary subaerial volcanic and sedimentary rocks (Marlow and other,1973).The early series is believed by Marlow and others (1973),and Scholl]and others (1975),and DeLong and others (1978)to be Eocene to middle Miocene,53 to 15 m.y.old.The middle series or middle unit consists of plutons mainly granodiorite that have intruded the early series.These rocks have radiometric dates of 10 to 15 m.y.before present (Mar low and others,1973; DeLong and others,1978).The late series,which consists of basaltic and andesitic.rocks that unconformable overlie the early and middle series,is up to at least 3 m.y.in age,based on radiometric ages from andesitic magmas (Cameron and Stone,1970). Coarse pyroclastic and magma flow deposits found througout the northeastern part of Unalaska Island,mapped as the Unalaska Formation by Drewes et al. (1961),were found throughout the region southeast of Makushin Volcano (Plate I).The dacitic rocks of this formation were usually found to be tuf faceous ungraded breccia flows,whereas the andesites and basalts were represented by magma and/or poorly graded breccia flows.These volcanic rocks grade into greenstones,having been altered by albitization,chloritization,epidotization, Silicification,and zeolitization. The region immediately southeast of Makushin Volcano,including fumarole fields no.1,2,3,and 4 (Reeder,1982),consist mainly of rock exposures belonging to the Unalaska Formation which has been extensively intruded by Quartz monzodiorite and some gabbro (Plate I and IJ).Unaltered volcanics make up the Makushin volcanic pile and most of the rock exposures to the northwest of a line extending from Pakushin Cone to Table Top Mountain.Plutonic rocks were criginally postulated by Drewes et al (1961)and later Sy Henning (Plate 1)to underlie most of these unaltered volcanics and a good part of Unalaska Island in general.Except for Pakushin Cone,the cones contained in the Makushin Volcano region have been subjected to intense glacial erosion.Both the Pakushin and Wide Bay Cones,which lack intense glacial erosion,are suspected to have formed since the last glacial maximum which ended about 11,000 yrs ago (Black,1976).The line of cones trending toward Point Kadin (Figure 1)and the corresponding extruded lavas are believed by Drewes and others (1961)to have formed within the last several thousand years;they based their claim on the lack of glacial erosion on the cones and flows,and on the degree of development of a submarine bench at Point Kadin. III.Detailed geologic observations including structural and gravity data, models,and interpretations. The contact boundaries between the Unalaska Formation and the intrusive bodies in the Makushin Volcano region appeared to be fairly complex.It was not unusual to find some of these contacts to be near vertical,and it was not unusual to find small bodies of intrusive rock interfingering the highly altered Unalaska Formation (Plate II). Prominent near vertical joints have been observed striking roughly N60°E, N30°E,N55°W,and N80°W (Reeder,unpublished data)as shown on Plate II and on the equal area Schmidt net joint projections (Figure 1)for the northern part of Unalaska Island.In fact,the fumarole activity of fumaroles no.2 and no.3 appear to follow a near vertical N60°E joint system which roughly follows the immediate plutonic-metavolcanic contact boundary in these two areas. Near vertical faults having vertical displacements of between twenty feet to several hundred feet have been observed in the Makushin Volcano region (Reeder,1981 and 1982;Plate I1).Most of these near vertical apparent normal faults strike N55-60°W,N35°E,and N85°E as indicated on the equal area Schmidt net fault projections (Figure 2).One of these N35°E faults trends directly into fumarole field no.5,and a N85°E fault trends directly through fumarole field no.1.Two N55°-60°W faults bound fumarole field no.2 as if they seve as impermeable boundaries,whereas one N55-60°W fault trends near fusrarole field no.1 and another similar fault trends directly toward fumarole field no.5. Near vertical dikes of undetermined age have also been observed in the Makushin Volcano region,having strikes that are very similar to the previously mentioned faults (Reeder,unpublished data,Plate II,and Figure 3).Such porphry basaltic to dacitic dikes cut the Unalaska Formation throughout the northern part of Unalaska Island (Drewes et al.,1961;and Plate II).These dikes,striking dominantly between N40°W to N65°W and dipping steeply southwest, are numerous in the central part of Amaknak Island and in the Summer Bay region, making up in some places over 50%of the exposed rock.Such a concentration of dikes represent an ancient volcanic rift zone which probably supplied most of the volcanic materials making up the Unalaska Formation.A few porphyritic dikes have been found cutting the plutonic rocks of the Captain's Bay region and of the Makushin Volcano region.Such dikes are geologically significant since they are younger than the Unalaska Formation and the plutonics that intrude this formation. Lineations observed in the field and also from old World War II air photographs also appear to reflect the same directional trends as the observed dikes,faults,and even in a few cases,the observed joints (Reeder,unpublished data;Plate III,and Figure 4).In most cases where bedrock exposures have been good all lineations have been found to reflect dikes and/or small faults.The lineation mapping,Plate III,will eventually be redone based on the high-quality air photographs obtained by North Pacific Aerial Surveys through Republic Geothermal,Inc.and the Alaska Power Authority. " These fault and dike trends appear to fit into a regional fracture pattern that in part is predictable based on the regional compressional tectonic stresses due to the convergence of the Pacific Plate underneath the North American Plate (Nakamura et al.,1977;and Reeder,1981).The Aleutian arc is part of a ridge-trench system associated with active volcanism and seimicity. The Aleutian Trench is located about 180 km south of Unalaska Island.Global tectonics has the floor of the Pacific Ocean (the Pacific Plate)approaching the Aleutian arc (the North American Plate)in a northwesternly direction at a rate of about 7 cm/yr (Minster and others,1974),where the Pacific Plate at the Aleutian Trench is being thrusted under the North American ?late.This underthrusting causes compressional stresses in the direction of the plate convergence in the arc region.For Makushin Volcano,Nakamura et al.(1977) determined on the basis of orientation of flank eruptions,a maximum stress orientation of N55°W where the expected azimuth based on the direction of plate convergence should be about N45°W.Based on this regional maximum stress orientation,steeply dipping dikes and normal faults striking in a N55°W direction would be predicted to exist along with some dikes and normal faults striking perpendicular to this direction;i.e.,N35°E (Nakamura,1977).A few near vertical dikes and numerous strik-slip faults striking about N80°E and N10°W:would also be predicted (Nakamura,1977).The only major deviation from this predicted pattern based on my own field observations on Unalaska Island (Reeder,unpublished data;and Plate II)is that the N80°E observed faults I\ appear to be normal faults instead of the predicted strike-slip faults.The predicted N10°W faults appear to be lacking although dikes and lineations have been recognized as trending in this direction (Plate II and III,Figures 3 and 4). A total of 155 gravity reading were obtained for the northern part of Unalaska Island during the summers of 1980 and 1982.The Complete Bouguer Anomaly Map resulting from the reduction of this data,using an average 2.6 gms/cc rock density for the terrain corrections,is shown on Plate IV.As shown on this map,steep gravity gradients in a N50°W direction occur in the Beaver Inlet region and in the Makushin Bay region where very low gravity gradients occur in the Unalaska Bay and in the Shaignikof Valley regions.In addition, large gravity anomaly lows occur in the upper Nateekin Valley and in the caldera region of Makushin Volcano,where a large gravity anomaly high occurs throughout the fumarole field no.l through no.4 region and into a large region to the immediate southeast. Preliminary 2-dimensional gravity modelling along profiles Pro 040 and pro 135 as indicated on Plate IV has been recently undertaken.This modelling has been based on rock densities determined directly from rock samples (Table la,b, and c;and Plate V)and inversely for the less dense unaltered volcanics by fitting spherical models to the gravity data.As a result,it has been determined that the Unalaska Formation has an average density of about 2.77 in the immediate Unalaska community region but a density of as low as 2.60 in the Makushin Volcano region where it has been more highly altered and its tuffaceous units are more abundant.The plutonics have average densities as low as 2.59 for the granodiorite to 2.88 for the gabbros.The unaltered volcanics were determined to have densities of as high as 2.86 for individual basalt flows to an average density low of 2.0 for the fragmented materials within the Makushin Volcano Caldera and for cinder cones such as Sugarloaf and Table Top Mountain. The results of the preliminary gravity modelling after removing a regional gravity are shown in Figures 6 and 7.In general,the large gravity anomaly low in the Makushin Caldera region appears to be due to the existence of a fairly large volume of low density volcanic materials whereas the large gravity anomaly low in the upper Nateekin Valley is probably due to a large sedimentary sequence /. of the Unalaska Formation.The low gravity anomaly that occupies the Unalaska Bay and the Shaignikof Valley regions appears to be due to a large granodiorite body,whereas the high gravity anomalies in the Beaver Inlet region and the fumarole field no.8,1,2,and 3 region appear to be due to fairly dense quartz monzodiorite and/or gabbro bodies. Only a few aspects of this gravity modelling will be addressed which appear to have major significance toward better defining the structure and geothermal resources of this region.For example,the gravity modeling suggest that the dense gravity monzodiorite body observed in the fumarole fields no.8,1,2,and 3 region does extend underneath the Makushin Volcano piles along with probably some metavolcanics,until reaching a Makushin Volcano rift zone (Figure 7). This rift zone is oriented about N30°E and trends from Pakushin Cone through the southeastern part of Makushim Volcano caldera and down through the northwestern flank of Makushin Volcano between fumarole field no.7 and the first Republic Geothermal temperature-gradient hole (Figure 7 and Plate IV).Such a rift zone is also substantiated by geologic observations by Reeder (Plate II and an unpublished Recent Extrusions in the Makushin Volcano Region map).Based on the gravity data,this rift zone is about 3 km wide,where the dense - quartz-monzodiorite continues on its other side underneath a fairly thick sequence of unaltered volcanics (Figure 7). Preliminary gravity modelling suggest that plutonic rocks in part intruded along steeply dipping bedding planes of the Unalaska Formation in the region just southeast of fumarole field no.1.The Unalaska Formation has a regional strike to the northeast with usually a gentle dip (usually not more than 20°)to the northwest (Plate I).Detailed geologic observations indicate small deviations from this pattern such as represented by a small anticlinal fold trending northeast in the Captains Bay region and beds dipping by more than 45° to the northwest in the upper Nateekin Valley region (Plate 11).Large meta- volcanic bodies that still retain their northeast strikes and their steep northwest dips appear to be nearly surrounded by intrusives as suggested by the gravity data.Some of the intrusive activity has probably followed weak bedding zones of the Unalaska Formation. The gravity modelling in the fumarole field no.1 area depicts a large graben trending roughly east-west (Figure 6 and 7;and Plate IV)which has a depth of up to 2km and a width of only about lkm as represented by altered metavolcanics.The southern boundary of this structure would be marked by fumarole field no.1 and by the recognized N85°E fault which passes through this fumarole field (Plate II).The northern boundary would be marked roughly by the location of the Makushin Valley canyon and approximately by the location of the first Republic Geothermal temperature gradient hole.Another much narrower graben is suggested by the gravity data to parallel this one,where its southern boundary would overlap Sugarloaf Cone.Such structures trend directly into Makushin Volcano and also depict a similar trend of the lower Makushin Valley. IV.Petrographic and geochemical analyses of rocks. The petrology and geochemistry of the volcanic rocks of the Makushin volcano region allow an evaluation of the extent and nature of volcanic activity at Makushin Volcano through time as well as help determine the character of any shallow magma systems.Such analysis extended to the plutonics and metavolcanics of this region could yield valuable insight into the nature of the country rock possibly being assimilated by intrusive bodies as well as insight into the history and present nature of hydrothermal activity. 'Quartz monzodiorite is the dominant rock type found dn the intrusives near Makushin Volcano as based on model counts (Table 2)using the IUGS J, classification of igneous rocks (Streckeisin,1973),where some gabbros and quartz diorite are also present (Figure 8).Plagioclase was found to be the most abundant mineral,comprising more than 50%of the mode for all of the rocks.Subhedral augite,hypersthene,iron oxides,potassium feldspar,quartz, and biotite were usually always found in appreciable anounts in these rocks. In many of the samples,the plagioclase was found to be sericitizedor albitized to some extent.Olivine was always found to be serpentized.In the more mafic intrusives,the augite phenocryst are sub-ophitically intergrown with plagioclase phenocryst.Chlorite,epidote,and even clay minerals (suspected to be kaolinite)were recognized as secondary alteration minerals. The unaltered volcanics of the Unalaska volcano region;i.e.,the Makushin Volcanics,the Makushin Volcano Volcanics,and the Eider Point Volcanics (Plate II),are predominantly basalt with subordinate amounts of andesite and pyroclastics and rarely some dacites.They typically contain less than 25% pheocryst of plagioclase and augite with smaller amounts of olivine, hypersthene,and/or more rarely horneblende (Table 2).Many of these rocks have been altered as indicated by the presence at several localities (other than in the fumarole fields which will be addressed later in this report)by silicifica- tion and zeolitization.Other more extensive alterations are strongly suspected and will be addressed as further petrographic examinations are undertaken. One hundred and four rock samples from the northern part of Unalaska Island have so far been analyzed for whole rock geochemical composition in the DGGS Fairbanks laboratory by means of X-ray fluorescence (XRF).The detailed results of the laboratory geochemical determinations are given in Table 3. High silica content volcanic rocks are usually indicative of volcanic regions which have or at least have had shallow magma chambers (i.e.,at depths of up to several kms).Also,because of the fine ground mass nature of most volcanic rocks,the whole rock analyses allow a positive identification of volcanic rocks.The silica content is the main basis of such a classification as follows:Basalt <52%;Basaltic andesite >52%but <56%;Andesite >56%but <62%;Dacite >62%but <67%;Rhyolites >67%. All of the vapor-dominated hydrothermal systems that have been developed into major sources of electrical power appear to be related to a rhyolitic heat source.No rhyolites have so far been found in the Makushin Volcano region. The unaltered volcanic rocks of the Makushin Volcano region are predominantly basalt,where subordinate amounts of basaltic andesites and andesites have been found in the Sugarloaf Cone region,the Kadin Rift region,and the Pakushin Cone region.A fair amount of andesites and basalts make up the Makushin Volcano where subordinate amounts of dacite have been found at the summit of this volcano (63.3%Si0>)and on its southern flank (65%Si09).Hot dacitic bodies at shallow depths probably represent the best heat sources for driving hydrothermal systems in the region. The "dioritic"intrusive rocks exposed just east and southeast of Makushin Volcano range in silica contents of a low of 51%to as high as 62%.The higher silica contents were found in the Glacial Valley region just below fumarole fields no.3 and no.4;i.e.,not far from where the highest unaltered volcanic silica contents have been found. In order to evaluate the magma chamber(s)beneath Makushin,selected major and trace element analyses were carried out for spatially separated samples of a wide range in composition by Charles Langmuir at Lamont-Doherty Geological Observatory.Sample locations are shown in Figure 9 and Plate V.The coverage is of both the peripheral and central vents of the volcano. Separately prepared powders of rocks had previously been analyzed for major elements by X-ray fluoresence (Table 3).Lamont-Doherty analyzed for selected major elements to ensure that their analyses were comparable to ours.The SRF and plasma analyses are compared in Table 4.Agreement is very good considering that different portions of the rocks were crushed and different sample preparation techniques were used.The plasma analyses for MgO are consistently lower than the XRF analyses.In the figures,the plasma values were used. The major element analyses generally show smooth trends on variation diagrams.One example is shown in Figure 10.The observed trends are not dissimilar from any other volcanoes of convergent plate margins,and would seem to be consistent with a single mechanism of evolution for the entire,volcano. The trace element analyses,however,reveal some complexities in the origins of the samples.Although there is a qualitatively continuous trend for most of the samples (Figures 11-13),in detail the variations are far more varied than can be accounted for simply by analytical uncertainty. The data become much less scattered when they are considered in terms of geographic location.Symbols for samples from the Table Top Mountain area have been filled in the diagrams,and they appear to be on separate trends from the rest of the data.They are relatively depleted in Ko0,La,and Ba,and relatively enriched in Sr.More important than the depletion in terms of over-all abundances are the differences in ratios suchas K/La and Ba/La between the Table Top Mountain samples and the other samples.Such differences cannot easily be generated in a subvolcanic magma chamber,and most likely reflect deep seated differences inherited from the mantle source regions.This would strong- Ty suggest that the Table Top Mountain volcanics are derived from a different magmatic plumbing system than the volcanics from the main Makushin cone. The three other samples,which are still from a large geographic area,may have been derived fron a single evolving magna chamber.These samples show smooth variations on both major and trace element diagrams,and these variations are consistent with what would be expected from a magma chamber which is cyrstallizing,and possibly assimilating material from the country rocks.The Mg0-Ti0o diagram suggests that Fe-Ti oxides became important in the crystallization process somewhere between 55 and 60%Si0o9.The gradually decreasing Sr content with increasing SiO suggests that plagioclase was an important fractionating phase,which in turn requires the fractionation to occur at low to moderate pressures. Volcanics from Makushin Volcano are not all derived from a single magmatic plumbing system.Those from the Table Top Mountain area seem to have been derived from a separate mantle source and to have undergone a separate evolutionary history.Samples from the main Makushin cone may be related to a large magmatic system which has undergone extensive crystallization and assimilation over a significant period of time.The current hydrothermal andrecentvolcanicactivitysuggestthatthissystemisstill'active. Ten samples were submitted to Stan Evans of the Earth Science Laboratory, University of Utah Research Institute for potassium-argon age dating.Because of alteration coupled with the low potassium content,six of the samples were undateable (Letter 1).No absolute age determinations were possible from the remaining four samples because no radiogenic argon was detected from these "geologically"recent volcanic samples (Letter 2).Evans concluded,based on the detection limits of his age-dating equipment,that three of the samples are less than a half million years old and that one of the samples (U-G-27)is less than 50,000 years old.The U-G-27 sample is an andesite from near Sugarloaf Cone.The other samples are andesites from immediately above fumarole fields no.2 and no.3 and a basalt from a volcanic neck located between the Wide Bay Cone and Table Top Mountain. Additional age-dating attempts will be made from the Republic Geothermal temperature-gradient cores. /) V.Volcanic Hazard considerations A fairly thick sequence of pyroclastic deposits occur in three valleys in the Driftwood Bay and Makushin Volcano region.These deposits are thought to be related to a major eruption event of Makushin Volcano which resulted in the formation of the 3-km-dia summit caldera (Reeder,1982).Organic material was found underneath these pyroclastic materials and samples have been submitted to commercial laboratories for C4 age dating.Because these deposits overlie glacial tills,they are suspected to have been emplaced since the last glacial maximum which ended 11,000 years ago./ Since this eruption event,no major eruptions have occurred from the caldera region of Makushin Volcano.It is highly suspected that the volcanic energy release activity of thé caldera region is actually in equilibrium with the large energy release from fumarole field no.6.If this is true,no major eruption events should be expected in the near future from the summit region of Makushin Volcano as long as fumarole field no.6 continues its activity.If such events did occur,there would probably be a fair number of large precursor earthquakes and other observable warnings. ) Flank eruptions especially on the northern flanks of Makushin Volcano could pose very serious volcanic hazards in the form of lava flows and heavy ash falls to any geothermal exploration and development activity.Such erputions have been quite common during "geologically recent"times (Reeder,unpublished data)and could occur with very little warning.Probably most of the historically recorded eruptionsof Makushin Volcano were actually from flank eruptions occurring near fumarole field no.7. VII.Conclusions including general drilling target recommendations In general the immediate Makushin Volcano region is considered to be a good geothermal prospect for large vapor-dominated hydrothermal systems as outlined in Figure 14.In addition,some smal]vapor-dominated hydrothermal systems are considered possible in the Sugarload Cone,upper Nateekin,and upper Glacial Valley regions as indicated in Figure 14 as a sub-geothermal prospect region. Deep exploration drilling is not recommended in this sub-geothermal prospect: region unless economic considerations completely rule out the possibility of deep exploration in the good geothermal prospect region. / Most of the unaltered volcanic rocks (i.e.,geologically recent volcanics) of the northern part of Unalaska Island would be expected to have fairly high permeabilities for fluid transport.Any heat originally contained in such rocks would have been removed fairly quickly by fluids with respect to geologic time, especially considering the wet environment of Unalaska Island.Thus,the driving heat sources for fumarole fields no.5,no.6,no.7,and possibly no.8 (al]of which occur in unaltered volcanics)are probably shallow magma bodies that have been en-placed within recent times.In fact,explosive activity within historic times is highly suspected for the fumarole field no.7 region (Personal Comm.,Henry Swanson,Unalaska)and is also suspected at a smaller level for the fumarole field no.6 region. Large vapor-dominated hydrothernial systems probably exist in the metavolcanics and plutonic rocks within a northeast oriented zone on the southeast flank of Makushin Volcano (Figure 14),where the southeast boundary of this zone is roughly marked by fumarole fields no.1,no.2,no.3,and no.4. The large N55°W,N35°E,and N85°E apparent normal faults which trend into the Makushin volcanic pile are probably the surface manifestations of dikes that did not reach the surface;ji.e.,at least for the region southeast of Makushin Volcano.Such dikes could be the driving heat sources for the hdyrothermal systems. By taking into account the geology and fumarole field locations,three suspected vapor-dominated hydrothermal systems have been outlined on Figure 14 as being within this northeast orfented zone.All three suspected systems trend ref underneath the Makushin volcanic pile toward its center along faults from the active fumarole fields no.1,no.2,no.3,and no.4 (Figure 14).At these fumarole fields,the vapor appears to be rising fairly vertical near the surface along near vertical joints and/or faults.Such a vertical rise could be occurring from depths of several thousand feet.Below such depths,the vapor movement is probably lateral as well as vertical. With respect to the suspected vapor-dominated system in the upper Glacier Valley region (System A,Figure 14),probably the N35°E fracture which trends toward fumarole field no.5 (Plate II)is the surface expression of a recently intruded dike-like magma body which could be driving the system.The N5S5°W trending normal faults which bound fumarole field no.2 could represént,along with the other northwest trending faults in the fumarole field no.1 and no.2 areas,dike-like magma bodies:Such magma bodies could also be driving the vapor-dominated systems.In the case of the vapor-dominated system C which includes fumarole field no.1,a large east-west structural trend into Makushin Volcano is suspected.Due to the lack of any evidence of geologically recent volcanic extrusions in the northeast oriented fumarole field no.1,2,3,and 4 zone,it is strongly suspected that any heat sources would be at depths of at least several kms and/or located laterally into the Makushin volcanic pile by at least several kms from these fumarole fields. Four geothermal drilling sites are suggested within these three vapor-dominated hydrothermal systems (Figure 14)where deep directional drilling (up to 2 kms)aimed toward the Makushin volcanic center would be recommended. These sites have been listed in the order of their resource potential.Drill site no.1 does appear to have the best resource potential as based on the gas geothermometer work by Roman Motyka and as based on the high silica contents of rocks relative to other unaltered volcanics and plutonics of the region (Plate IV and Table 3).Such "higher silica content"rocks suggest the possibility of "hotter"heat sources in the suggested regions.Drill site no.2 was given a high second priority because it lies along the northwest Makushin Volcano-Point Kadin rift zone which has also extruded some fairly high silica content volcanics.Drill sites no.3 and no.4,a region originally suggested by Reeder and others (1982)because of logistical as well as resource potential considerations,are located next to fumarole field no.1.The structural setting of this region makes it an interesting geothermal exploration site. "Vapor-dominated"hydrothermal systems might exist in the fractured Unalaska Formation and/or in the fractured plutonics that underlie most of the unaltered volcanics of the Makushin Volcano,as well as in or near the actural Makushin Volcano conduit system.Drilling into the N35°E Makushin rift zone could be technically difficult.Northwest of this northeast rift zone,one to four kms of unaltered volcanics exist on top of plutonics and/or metavolcanics as based on gravity data (Figure 7).Drilling through this unaltered volcanics would aslo be difficult.Yet,based on our geochemical isotope data,the Makushin volcanic system does appear to be one large system having one large magma chamber between 2 to 20 kms depth.The temperature gradient for the immediate Makushin Volcano region would be expected to be quite high (as partially substantiated this last summer by Republic Geothermal,Inc.).Thus, the possibility of large vapor-dominated hydrothermal systems underneath the Makushin volcanic pile (as marked by the good geothermal prospect region in Figure 14)should not be ruled out.) The sub-geothermal prospect region has also been included because small vapor-dominated systems most likely at depths of 2 kms or more could exist in fractures within the plutonics and metavolcanics of this region.Hot rock and some vapor transport at fumarole field no.8,a geologically recent relic fumarole area in the upper Nateekin Valley,and fluid geochemical findings for hot springs in the upper Glacial Valley all add some support for this possibility.The significance of this consideration is that,for example,the cost of drilling a deep vertical well near Sugarloaf Cone using the driftwood air strip as a supply base would be substantially lower than drilling anywhere in the good geothermal prospect region.But,the resource potential of the good geothermal prospect region is without question much higher.It is seriously doubted if any large vapor-dominated systems extend beyond the fumarole field no.1,2,3,and 4 region (i.e.,beyond the good geothermal prospect region). Outside of the good geothermal and sub-geothermal prospect regions, vapor-dominated systems are possible but unlikely due to the low-silica contents of the geologically recent volcanic centers which suggest cooler heat sources It, and a deeper mantle magma source.In addition,there is the lack of any solid evidence for the existence of vapor-dominated systems in this region. ) References Black,R.F.,1976,Geology of Umnak Island eastern Aleutians as related to theAleuts:Arctic and Alpine Research,v.8,no.1,pp.7-35. Cameron,C.P.,and Stone,D.B.,1970,Outline geology of the Aleutian IslandswithpaleomagneticdatafromShemyaandAdakIslands:University of AlaskaGeophysicalInstitituteandDepartmentofGeology,UAG R-213,152 p. Drewes,Harold,Fraser,G.D.,Snyder,G.L.,and Barnett,H.F.,Jr.,1961, Geology of Unalaska Island and adjacent insular shelf,Aleutian Islands,Alaska:U.S.Geological Survey Bulletin 1028-S,pp.583-676. Mahon,W.A.J.,Klyen,L.E.,and Rhode,M.,1980,Neutral sodium/bicarbonate/ sulfate hot waters in geothermal systems:Chinetsa (Journal of the JapanGeothermalEnergyAssociation),v.17,no.1 (ser.64),pp.11-23. Marlow,M.S.,Scholl,D.W.,Buffington,E.C.,and Alpha,Tau Rho,1973,Tectonic history of the central Aleutian arc:Geological Society of America Bulletin,v.84,pp.1555-1574. Minster,J.B.,Jordan,T.H.,Molnar,P.,and Haines,E.,1974,Numerical modeling of instantaneous plate tectonics:Geophysical Journal of the Royal Astronomical Society,v.36,pp.541-576. Motyka,R.d.,Moorman,M.A.,and Liss,S.A.,1981,Assessment of thermal spring sites,Aleutian arc,Atka Island to Becherof Lake -Preliminary results and evaluation:Alaska Div.of Geological and Geophysical Surveys Open-File Report 144,173 p. Nakamura,K.,1977,Volcanoes as possible indicator of tectonic stress orientation--principle and proposal:Journal of Volcanology and Geothermal Research,v.2,pp.1-16. Nakamura,K.,Plafxer,G.,Jacob,K.H.,and Davies,J.N.,1930,A Tectonic Trajectory Map of Alaska Using Information from Volcanoes and Faults, Bulletin of the Earthquake Research Institute,Vol.55,pp.87-112. Nakamura,K.,Jacob,K.H.,and Davis,J.N.,1977,Volcanoes as possible indicators of tectonic stress orientation -Aleutians and Alaska,Pageoph, Vol.115,pp.87-112. Reeder,J.W.,1981,Vapor-dominated hydrothermal manifestations on Unalaska Island,and their geologic and tectonic setting:1981 IAVCEI Symposium - Arc Volcanism,Volcanological Society of Japan and the International Association of Volcanology and Chemistry of the Earth's Interior,pp. 297-298. Reeder,J.W.,1982,Hydrothermal resources of the northern part of Unalaska Island,Alaska:Alaska Div.of Geological and Geophysical Surveys Open-File Report 163,17 p. Reeder,J.W.,Economides,M.Jd.,and Markle,D.R.,1982,Economic and engineering considerations for geothermal development in the Makushin Volcano region of Unalaska Island,Alaska:Geothermal Resource Council Transactions,v.6, pp.385-388. Scholl,D.W.,Duffington,E.C.,and Marlow,M.S.,1975 Plate tectonics and the structural evolution of the Aleutian-Bering Sea region,in Forbes,R.B., ed.,Contributions to the geology of the Bering Sea basin and adjacent regions:Geological Society of America Special Paper 151,pp.1-31. Streickeisen,A.,1976,To each plutonic rock its proper name:Earth Science Reviews,v.12,pp.1-13. White,D.E.,Muffler,L.P.Jd.,Truesdell,A.H.,1971,Vapor-dominated hydrothermal systems compared with hot-water systems:Economic Geology,v. 66,no.1,pp.75-79. / APPENDIX A -FIGURES 9 wal Bre a Schmidt Mer Veint $ Northern Pack of Unelaske Islanol Blaska Figure / N Egae/BereaSehmidtNel ry]60 Ww Ee 90.Fo $0 'Faults 'Morthern [act .oSUnalaska Island ¥0 QL ge 0 1d 60 |Egael AreaSchmidtWet 'Ny "Jo - pe % ebid¢et ye €ol a - e t ee if l&e e mo -OY +e ,é vA -_/ ®*,im 2 Kee-or s yco°Pudid ox |Od +,ee_*Os,( io a 2s 10 5 Nocthees fact eS§ ve Knalaske Delon! 27....be Fy ae*30 Pikes 130 ge ey"ec @3 >>'40%e@ ss og?bd €vad ae"©?¢.J,4(7eer©L @B%[72 Oy 4 we Os of Ss .©+Z 7 --os y-™("2stbee a 2(atve. ea ,we?oe -s-eo:rele -_-a *_el__-___-_, e EE &o e Das .e "2 %e foal oa ava€eo 'A +> ,-%460 ./28 "&a ee NON a 47 1e6 ¥0 a}e a.Ad AI>be iv 20 pee Sein A A yg MENA,;2 ee Ay 'ane Xy .yo SN ':otsSaySATEANSRO*NeeRo)=Noe + * ueSRx AsSRENEKEIRCOE.oN SS PERSEN miesYSPENS 'ei ”in Ge.Py +OREN Ie me blMido be ee Zs v fi iH sf,,"te \| oi -\AS . AZIMUTH OF MARIMUM St dy tag,See 7 'Im oy heHORIZONTALSTRESS* ) .' Lower |: |- a &' QUALITY - emmeenn HIGHER ' te ena.)\ VULCANUES &VULLANIC FILLOS "SS.@ a.1 BERING .LATE QUATERNARY FAULTS ra |. :%'SEA é ee |rN .'a,IVa ' :5 ta.135}156 werkt. co ;USB oe Ly O 4 ,.oe,'a!sat ve &my ais ;'9y ' .i'ty °-soom hE j 1000 KM 1 dee.'i [1 pt!,i Rn )\(heb gat,4 '| a %PA ¢/rf e€ SOREN Nap of the late Quaternucy (eclome slress trajectories of the Aleutlinns and Aluska,to ty)teclonte atiess helds, (Mingten ef al,197) und Sear,Wid.Ch: Dula in 'Tables bo and 2 Stress Gajeclories (atippled lines)represent averaged directions of MING or odfasa,which can bo uther ay or ty. Sinuvua duuble line locates spprostnate boutdary bebween campressionl (addins a? oi)td catensonal dedbiwe -ay, Open arrows:directions of motion of Pactie plate celutive du North American plate Square and bar show the epieoiter and Hawt of an canthqaake of noctial fult ty po (Sykes Chirihuv boote USL er,Nakamura exal ,(78 ,Leg whe o Terr” Gravity Prof ile v0"ten fer clockwise Ss ol aw' ) * , ,lol Kon'aé Fa bd neon unt . pt ol ;1%,theongh Fumareles on SE side of Makush Valeane ,Analasha Deh Xa |NN v\yySPTq SN +20 -'tN yy \ |0 |TRY \A Xo K |°an:Ms i |oe 8 +10 «M all }hi ra on,©--oO,NY M '9 Q from =J a a 9° 9-7 ON,|| X wad Y Y fool "eo y-nN ©we i) "\Y 'a}vas ay ae 0)Y %Ox |[.ro Ss Saaieemocireols >I ,\j |ya ---SA | -7 4 |''.Gan, "(6 «2 ee :'\.sf t co Qo -20-eine thereetienf :A y Oo oO ;Dbser a ;)mot Y ,ij 7 |;|a :Fj !an) ay }reac pb 1 ryde ; rip,|Hot de | KM Chertroate!Aveta we \.; 0 '9 ;a ;Jol , 'Be Rt 40 47 28 32 /wt!.gt |i {.i \i i {ot : 36 YO Unalbered Ve Caare '1 Lo my Lob,bart |3%;Ie N L.so ad [12 A 'Vf iteced velcaai edGEisinLLeneeneeeneaOL 1.6 nT aan --| 199 7 pow)pe |pi ob |257 Unalleced velcence 2.67 roa Seen eens coe ;2.82 2.62 +o ;Kiker ed |Mella velcante |po .i |Hitered Unalashe Miter,Altered Metovelcasic ants, andi |ci !ro 4 os :\rralesh Beavnediocife wor Yo :7 "El 2.67 's Cranedistile |L 1,90 ;ty fi ake 'it |:Buart2 Monzoder:le 2.77 ' i 'to Ga bheo Hor Sels al,Quartz '|| Morr oterité ”:| H Talwaae 2-D model ol AhTT Profile =»”Counter clockwise from d bast10© =OO”a,noes Fo |>u ta sha g/a "oy 3 )\ana ”K A %$\ry S 4 yyo\Q pes).x !.AY|_)0 20 =Yy ;gS ,a /aN N |S S)aoNy'CCSofrnSenn:y x Nv i ay S aaaeayace\eeyowESfiemanneaed17. ; ; sa ©Oa Ge 6 OO fo)dS 4.x ---dn 6 rere ©theoretical _-|i !''L : ,y k©@ Observed (sag be sean!os Unalas 4 "10 'ged iment 7 244:albered mela velcunies ,KM (hoes aonla/distance)”ar or ;,ig '- 0 1 6 gg ge 30 3Y 38 924.N 1 a get i i L N ;i 'peo -Unallber ed'toe L |'|eeVolcanies2.00 |mrad zya-'.| i td i . :."T™Beart__.:.:i .'2.465 |; ;Monr2ed orc,KM Spb,'Grane dierite :.257)ands. :of t :ana : !;W/)M dive ,ds -ae 4 bebhr od .i my needs onze 100k Annet Monzs weite .Gran otters ze64.nee 7 Le!ba bbro -oo ;; y \'{.t i fl ' a 2.80 Vol Cancs i to.i |'' ; | Pn ¢4 Ch rece at):. .'i a . i 'Guacle \3 f :\Monzodiorite Lo A : < i 'j :fT !'andr : Se '' , to ': bibbeo ;;ro!. |CraneLeorale ;po Fa \'|;iL|t +Captains Ba Plate,after Michae/Peedit ov Deewes ata/, oO Meakushin Velcane P/latan "Stee Reeden 60 Geanodjecite 40 Qasclr Quartz Monrenil?e Oreeite Qual,Moozediente ws dN VNPlag"io re Fae ss [hanna Po a5 9%Ik-Se/d spac UNALASKA ISLAND )e-lTahel/ u-20/-kI G38 bl LAR Qh - OL -203-2-/ 0 5 10 =-15mi |i 1 4 __JI 'fT [|q 7 N Oo 5 10 158 20km . Figure 7 NazO+KoOA 6.0 5.0F A 4.0r A 3.0 ]in i |I L 48 50 52 54 56 58 60S102 1guce IO a 1.60 1.50 1.40 1.30 1.20 1.10 KoU1.00 90 Fig 10 b lOF 1 1.3 fig We 17 16 ODit I _j I LO Ll K20O l.2 1.3 1.4 1.5 1.6 JI600 900 400 4 -4 ya "gure 2 A A A Lf !1}1 1 1 1 \ 6 10 tl l2 I3 14 15 16 17 ' s or - -domineteas "hy dectherm il iO) -{ f :oN!yu' i ; 'J tft a ° an oo _ = . .oe tap --a as )Orn hecme fe me poet Wl 7'-; ' ;&-w rho Oe whes QV s6ie. \i\.SS- N Lge7eS Serer ae ! : abe gE hadol Ming SEAV St. settee 8, vif(ttIQC}:iul OTge TRE)Y 5 BL tS!| ire z rs 4 '¢ toga , m4 okpttoedog,oarVw=. l . an| io pt ' \ \ te! |if\ af, 1oe ' i! C 5rm " H% t\ ' "7y _* !heya{\\'é4 27° roy a" ope\he =a o> NY 'Ae m, ,( ' ; ras - \ ' soe , a in pa NX[ \ '{'v8 . voy or are pest x ax1 ' wih? . ;f© \z hens|a | we ae FS ' {*oe+a_{.1xXe, oA TTP ewe ey | x He epBaTY a> aaSee veers7eea ''| u/ . ' . omnes AY yeDyry, (tNoe ao RSwane co wa teh 1|:Ww{ , Ps:: ; boa ee ee . ota etH"1oh Ss1g / ' ' a " \k1 '' F - if , : toe : Q : 5 py '' _ SOP heopSek RR RO8 Ais |yaach eee SS om| ' | ' | ';Sp}\ haFilouc? APPENDIX B TABLES CHEMICAL &GEOLOGICAL LABORA1sORIES OF ALASKA,INC P.O.BOX 4-1276 TELEPHONE (907)-279-4014 ANCHORAGE INDUSTRIAL CENTE]! Anchorage,Alaska 99509 -274-3364 5633 B Street ANALYTICAL REPORT FromAk.Div.of Geological &Geophysical Surveys 4,Rocks Address Anchorage,Alaska _Date October 39,1981 Other Pertinent Data November 5,1981 tab No.9335AnalyzedbySEDate REPORT OF ANALYSIS ROCK SAMPLES UNALASKA ISLAND,ALASKA Samples received October 30,1981 SAMPLE DENSITY,grams/cm>@ 20°C 1-R-8)2.707: 17-S-1 2.758 502-R 2.713 86-R-1 2.851| 99-R-1 2.815 91-R-]2.768 ,500-R 2.700 .U-93-R-1 2.861 © 91-R-2 2.752 > Jabse la CHEMICAL GEQLOGICAL LAPROR"*OFIES OF ALASKA,INC P.O.BS&4 127€TELESR ONE (O07FTett ANIEOCRATE INDUSTRIAL CENTE Anchoraxy ,Alasae E5502 2764 328+FEISS BE Stree ANALYTICAL REPORT -£---_--= Fron.State Of Alesxe-ert.cf Natural Fe!Product Finck 7 Addres.Anchoress,AISSh2 Date _Serptecer 1€,JOES2 _ Other Pertinent Data Analyzed bs sf REPORT OF ANALYSIS -ROCK SAMPLES ANCHORAGE,ALASKR Samples received September 16,1952 AMPLE :SPECIFIC GRAVITY,an/an 1210-1 2.731-173-R-1 2.69U-194-R-4 2.67U+194-R-3 2.81U-143-R-1 2.8429-R-B1--M 2.5927-R-81-M 2.6023-R-81-M 2.75U-186-R-1 2.78U-192-R-1 2.78 U-6-38-6 2.10 U-G-45 1.43U-34-S-1 2.68U-173-R-1 2.67 U-G-27-1 2.63U-194-R-5 | | 2.77 Tbe th CHEMICAL w GEOLOGICAL LABORA.IRIES OF ALASKA,INC. P.O.BOX 4-1276 TELEPHONE (997)-279-4014 ANCHORAGE tNDUSTRIAL CENTEF Anchorage,Alaska 99509 274-3364 5633 B Street ANALYTICAL REPORT From St.Of Ak.Dept.of Natural Resources =pogue;Rock. Address Anchorage,Alaska Date October 26,1982 Other Pertinent Data Analyzed by SE Date _October 26,1982 Lab No.826 REPORT OF ANALYSIS ROCK SAMPLES UNALASKA ISLAND,ALASKA Sample Received October 26,1982 SAMPLE IDENTIFICATION SPECIFIC GRAVITY,on/om?ERROR +,gm/am? U-N-4-82 2.52 0.04 U-N-7-82 2.69 0.01 U-7-R-82-1 2.69 0.01 U-7-R-82-3 2.59 0.01 0-9-R-82 2.69 0.01 U-11-R-82 2.72 0.01 U-13-R-82 2.75 0.01 U-18-R-82-1 2.76 0.01 U-22-R-82 2.83 0.01 U-25-R-82 2.66 0.01 U-28-R-82-d 2.45 0.01 U-31-R-82-a 2.63 0.01 U-36-R-82 2.77 0.01 U-42-R-82 2.48 0.01 - U-61-R-82-1 2.90 0.01 - U-61-R-82-2 2.79 0.01 U-62-R-82 2.85 0.01 U-63-R-82 2.86 0.01 U-73-R-82 2.82 0.01 U-204-R-82-C 2.73 0.01 U-206-R-1 2.71 0.01 U-207-R-82-BI 2.87 0.01 lable le €o oe 7 i feeder E Dog =;=3 4 .€ ''i ,:i ps :oe |heck sample ifere eel |heecee 7 ferceat \fercenl i fereenl lee,ent:-ere eee rn es rae 7 :.eth |htmuokesphereceystiphsicchselaugite ingsersthese eherne |Mise.|''frame <ffl ;i . ! 1 - y j |i i | Tn ry i |i |-||i 'is.!i c the [4O-f-/-Sy A 1 |va &,7 |,a 7 :ec ee ee,LY ANZ!tof 72 en Le 6 ae /,ya a --- a ee ee ee on «,olivine eugle jt bb yewnstee -_5!1 betall si ;;: c Goi |, _,if i : :.:;S$rele MO TELAPE eB ||BR ee! Bo oe po |=ot fo behing aug fe ||bylewnite|!enmt|basal |bog |Jt.|_a ny i i ro |:|opel ore >-ft ne ws.[|VE i |nib.|U6-27 be ||ee|Ae eo Le || 1B |Peld dobe peep foot ee tbe ft magnetite |{:4 wt 7 ::!Doi Do :iy :"Aypersthene aueite it andesine |eee tt i ne es :me oo |e '4 j i ' "5 Peseleia endlest€i _-+-| D :I a Jit 2 bY yios | _:e5281b63¢-s |Be |lines |ce Ose | 18 ee ee ee eee wer mehte |:H ;;poe i.|' '18),eagle andesite |labradorite}:L |Le 20°a i feedesine'|po!\i:'4 _-----;-_t j ! 7 |'i :,fo,:i i 7rapeto: -T :os TIF 3 ra oer ae ; 'oT Tyalg|AW e-18 Abe |ng |ee |BAI Beer?)nen!:;' 4 :; " 7 t ;1 H :23 |po tl.sleet d bibbia:fad f}iGi ft ttlengeTypersthene|)brace)itr TET fg |t "-Ta i--t t ;-osastSacreeeeandesioe|il fiii f tf head Pad gi |ae HE S5enm eeeeeelizeyaai$4 a oy24lies7-s-2 |eee ||ee |ike A |se |se |; ::'i v4 . |i i 14 {a :Pou :H-__laytersyheae olivine,||-pt a are att eeri:i ij pau : :|tt :287 aate basaltre fo ttl Wabredonvel tl tt .itieeeTro'°Tt 7 ; :'H 4|!poi fide td fet ge ||eeeoeTT,TD =>»e*TF 1 "7 :Te oot :tae1U-Se-o-/|te)ee ea |AA!a ||eho fale ou :egnet.te_|| _7 7 on 7 4 ' : : 7 'iw staiAugik€ol tn ¢i labradorte ||hat on ':: 1,&i t .1 -35)i base lve anwdeste |ii i bit pi dat fi ri 3 \7 _:i fy toa i |'{H 'i t i !:i36)Seen ee eee Ls|TTP:i Pt fo a riod;i |od"|--Boa RR EP RE DS ED EAE ON TEA SEES BEE38}!j ott it ||oi|-ae me -s VT H ,::.i .cs i |39 ' i |:{t t |u {:ieeeO ee - --!_aoa t--+4 7 --7 7 'i }"0 ; _i patie ATIi'1 '4 !j . ; {j proi _ :|ii :: ' .{.eh Fence!Thaw.ele __..ee Lhedes bee _uneltered wceltaaic eck é + ry fo.L6ne/aske ZL Slane! ORO f "a TOS ec ks £8..the Foe hastiaq -h , Cer ses (E27 5. j----+- NGaertz dior:CE Bele,|bene.|lpegaeJiLaw -ine eghe Ssh C,Plesrei _ee EEL ---=er 2 Lovee M23 =ee =a:€ eck Semple oe : ||heater runbel |ee a[eme e¢phed |'! po ___Vbsgetchut,Intechiae baetdr |Bae |Bagate |Bypecstieneee29277PsodeinsooCBeemuneveOMTGpBae |ft Ag |Eebeef[legirelach Latigeliat|biaarfe |Laue hy Pecst\cy a oa --_-{"bethee hese -fyper s they 7SLee- --_|babs ro me | oe eh MARE _a Guecri2.mort,ert] eat 2.7c¥06 |840)|SA.)8A |34 |FS : ,|1 |i i :., t 1 CZ2 142 °Upe ge ahd i WL or wa :. |'H !j 3 z re ,:AG ; po :' : :;i i ::ae ;iZ i fig tl pt 4 fr ro ene ae -°7jpigaecizmerehere||Aknte |pape |Checex !: };: :;<.f i : . i i| ::fi : 'rot :|!:|i : t :i '+:tpomerane-T --wae we He Tot tT t cnaumnediiionen af -JT _4 7 1 i '' -i : eo |1 oe _!t !|a an i vai :.!:: :T j =- _t 1![_YaLIS ATS ©Wilson sours ramen GIS CREE Fane Mee pit EP,PULV (-)(+) |MIN SEP .RETAIN PULPS?P i 74.;ROCKS | :ELEMENTS/METHOD:Si09_Alg0a.Beat MnO MgO x0 Neg Kaa.Tid Cin0g/anceps BATCHNO,=3 Cu Pb Tn Wo Sb Ni Co Cd Mn Ag -Au7AAS(1)(3)©F,Cl./AISE/ARF DATE INS feb Dal OUT_sLe/eBeScYTiZrVNbTaCrMoWMnPtBGaInGeSnBi/SPEC/XRF IADGGS REPT.NO. [sven NO.;LAB NO.oar Si09 Pe903 (Feo Mao MgO |CaO ee CO2 | W U-I-R.L /2s ®43.3]3.44 Goll 2 |2 ezl e726 4.34 i UrR L 2b *®65.97 2.82)1.37)973 17-79 |2.34 3.4/ Dvi/-e-2]27 8 |Zeus 2 |»s¢}.03 |=|98 L42 U-Y-R LiwvzB *4727 3.08\¢.97|79 |6/51 2.43 2-66 |U-S k-I L y2q_*%SLL 3.72|4-921..27 LB0|BS |2.26 UY RL Li3z0 ®Y9.6S gut|4.99]76 |s.2/|922 3-16 __] VAB-Re bap 25.42 164 |Zo ys |49 |24 3.27 U-23-R-t |3e ®54.87 3.40 |svelise |¥2s|ZI 68 We oeki|Ih 1/33 R so.sS\as7 la Jal ssl s [dre |707 5.06 (U-26-R-a |B 34 ®69.10 2.391 3M ley 12s |6.28 LY Uz Z27-R.L y3s7_60.53 202|2eeli77 L720 [5:67 LK On 34-4 Ly3zo ®54,43 1201 53/1472 |3.47|750 2.07 U-3Y-Bes L 37 ®L017 336 |3.20]7 17.68|4-78 3.37 U-37-8."#36 2%Sf Ht 2.33 |477|5 [4-51 |946 1.85 U-4|-R-)Loy37_®$2.03 277 |2.2070 |2015.26 1.2% U-42-R-|L iyo _*®622814 L69\LD 2 OS NATE ZI LSE | U-45 R-|L "fy;CLOd AB2z\2G4 io¥|Zo?|i 4/LLG (Y-49-R-|L 1/42.SSI 467|2.93)ff (F784 TY |Le0 | US2-R-|L (/Y3 L7 4.67!7.32 Wt.5 4.43\|F%.%0 le W-Ss-R-2|1B dy PAPA eri SAE)Tees AS 22 |e1 78 dad BeetRTpeoe RETAIN PULPS?PREP.PUL()(+)-MIN SEP PZ 4 Roc : _ELEMENTS/METHOD:(53,0208 Fe203 MnO MgO CaO Nag0 KO TiOoCra09/SAS(4)/KRFPEA "BATCHNO,3.3 a Ha As GE Pb Zao SiN Go Gl tin By AIAASOVO),Fol ASE/KRE DATE INZS/BA/_DATE OVE_'Be Sc Y Ti Zr V Nb Ta Cr Mo W Mn Pt B Ga In Ge-Sn BV/SPEC/KRF W/XRF IADGGS REPT.NO. reco no.|S}ago,|DATE]DATE)DATE|DATE a Aty83|Si02 |Alg03|Fe203|FeO |MnO |MgO |CaO Nag0}Kz0 |P203|TiO2 619091 2761 H20°|CO» §)USER L 4s %P9-D '1 5¥.2/|p02 |2.69 456 f614.25|42)3.70).99 >|92 G2 _ S U-bs=h3 L 146 *®2 0./3 4.21 1/918 |9.46 4.51 15 4.50 |2-5317.39).99 |297 1 75 12403 p'1U-8 -R |L W477 *92.93 'leomle re2l 2.95!Z29l is beer lyre level costs [73 |IWC t U-7o-Ke L HY 8 R 27 92 CLIT9 V6 ISI ASE 3.20174 |79 5-49 \3 24)2.091 0/9 )-638 \L227 A U-89-K-|L //yq_®00-05 SF GOH 29 464 4 14\77 13.73 16-95!3.481759 1.21 |9s ;j20 : |U-9/ Re Lyiso 99.93 53.991 77372|4.391 £64]79 [¢2/17.s513.s6|425 |23 |470 LAs | "U-78-R-|Lusi *®97.23 SAS 1.54 2.04|s251 7%|y29 748 |3.301767 |22!os Lz ! *U-/oo-R-|Liye ®99.59 50.7612 G19:S11 2.94)AS |pey |9-36 148)77 |re |88 a-2b |Uoiig R-2 LW/5s3 *79.92 suse |risdgee |gal ire |asl goslaye|9s)27iAe7 V9 W)U-137-R-]L jis ®peopl lS2.3lvevA4dl3 |294l.09 logsl sve |y23|469 |.22|277 21S. 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Altered,whole-rock date would give minmum age,I]wouldn't date this one. Plagioclase altered,calcite abundant,don't date. Olivine completely serpentinized,could yield minimum age on @ whole-rock date,a fresher sample would be much better. whole-rock date. Olivine completely serpentinized,plagioclase might yield a reasonable date if it remained closed during cooling. wnole-rock date. Plagioclase could be dated here. Wnhole-rock date. Olivine serpentinized,plagioclase could be dated. ° All of these rocks appear to be fairly basic,basalt-gabbro (?),so dating plagioclase very low in potassium could be a problem.If you have pulk cheinistry on these rocks it would be helpful in deciding whether separating plagioclase would be worthwhile. Letler 7 If you have sone coupcsitione]date please call.I will begin processing 1thethreewhole-rock sameles now but will hold off on the others until 1 hear from you. Sincerely, Stan Evans SE /jm Letler [ UNIVERSITY OF UTAH RESEARCH INSTITLTE UURI EARTH SCIENCE LABORATORY 420 CHIPETA WAY.SUITE 120 SALT LAKE CITY.UTAH 84108 TELEPHONE 801-581-5283 September 27,1982 Dr.Clay Nichols Alaska Division of Geological and Geophysical Survey3001PorcupineDrive Anchorage,AK 99501 Dear Clay: I have completed running the four samples we decided to try.The threewhole-rock samples (U-152-R-1,U-194-R-5m and U-208-R-1)all failed to yield any detectable radiogenic argon as mentioned in our telephone conversation.IrecentlyranaplagioclaseseparatefromsampleU-6-27 which unfortunately also failed to yield a detectable radiogenic argon.Based on the detection limit of our mass spectrometer I would speculate that all these samples areTessthanahalfmillionyearsold,possibly much younger.. I regret that all the samples failed to give any age information but this is a risk when dealing with whole-rock samples which are very young.The plagioclase separate was a bit of a surprise,usually you can pick up some radiogenic argon in a mineral separate if they are over 50,000 years old. If you have any questions regarding this work you may contact me through ESL even though I will no longer be with them after the first of October.- Sincerely, Hew Frans S.H.Evans,dr. SHE:jp Lertler 2 APPENDIX D PLATES Wee USHIN VOL@AWO OOS GEOTHERMAL RESOURCES Informal Report submitted to the Alaska Power Authority by: John W.Reeder,Ph.D. Roman Motyka Mitch Henning Clay Nichols,Ph.D. State of Alaska Department of Natural Resources Division of Geological &Geophysical Surveys November 30,1982 a Proj.Code: Fite Code:SOO 7. el J.Cate: 2,SSY./ MAKUSHIN VOLCANO GEOTHERMAL RESOURCES Informal Report submitted to the Alaska Power Authority by: John W.Reeder,Ph.D. Roman Motyka Mitch Henning Clay Nichols,Ph.D. State of Alaska Department of Natural Resources Division of Geological &Geophysical Surveys November 30,1982 o Informal DGGS Makushin Volcano Geothermal Report,November 30,1982 I.Introduction II.General geology and geothermal resource review (Reeder) III.Detailed structural geologic observations,including gravity data,models, and interpretations (Reeder) IV.Petrographic geochemical analyses of rocks (Reeder and Nichols) (A)Preliminary petrographic evaluation,geochemical evaluation,and potassium-argon age dating (B)Hydrothermal alteration and clay mineralogy evaluation V.Volcanic hazard considerations (Reeder) VI.Geothermal fluid investigations of the Makushin geothermal area (Motyka) VII.Conclusions including general drilling target recommendations References Appendix A,Figures Appendix B,Tables Appendix C,Letters Appendix D,Plates I.Introduction The purpose of this report is to summarize the studies performed by DGGS during the 1982 field season in the vicinity of Makushin Volcano,Unalaska to the Alaska Power Authority.These studies included:geologic mapping, geochemical sampling of geothermal fluids,detailed structural and gravity investigations,petrographic and geochemical rock investigations including K-Ar age dating and clay mineralogy determinations,and initial volcanic hazard considerations.A preliminary drilling-target recommendation section has also been included as representing the summary and the general APA purpose of this report. "! 'NA II.General Geology and Geothermal Resource Review }pte te;newer ve "af,}4é/al,:iG '', oat *Cog tan ede el ee se ye Fumaroles occurring in the Makushin Volcano region of Unalaska Island,many being discovered in 1980 and described for the first time by Reeder (1981 and 1982),are direct evidence of vapor-dominated hydrothermal systems.The term "vapor-dominated hydrothermal systems"was originally coined by White and others (1971)for those systems in which the reservoir fluids are mainly vapor,not liquid;i.e.,wet,dry-saturated,or superheated steam.There are only a few places in the world,such as The Geysers,California,and Larderello,Italy, where hydrothermal systems consist mainly of vapor.These systems have been developed where they now represent the major source of electrical geothermal power.The ""vapor-dominated"hydrothermal systems in the Makushin Volcano region probably consist of wet steam. Some warm and hot springs were found near the fumarole fields at lower elevations (Reeder,1982).Initial water analyses of some of these hot and warm springs (Motyka and others,1981)indicated near-neutral sodium-bicarbonate- sulfate waters similar to hydrothermal waters described by Mahon and others (1980),which consisted predominantly of meteoric waters that had been heated by vapor-dominated hydrothermal systems generated from greater than 150°C alkali- chloride waters at greater depth.The hot springs in the Makushin Volcano region probably derive most of their heat from the vapor-dominated hydrothermal systems that are the source of the fumaroles throughout the region.In some cases,this type of relationship between surface waters and hot springs can be seen directly in the field. The rocks of Unalaska Island include an older group of altered sedimentary and volcanic rocks designated the Unalaska Formation by Drewes and others (1961),a group of intermediate-age plutonic rocks,and a younger group of unaltered volcanic rocks.The three groups can be correlated with those found throughout the eastern and central Aleutian Islands,namely,an early series of a marine volcanic and sedimentary sequence that has been matamorphosed to a greenschist grade,a middle series of plutonic rocks,and a late series of an unaltered sequence of Tertiary subaerial volcanic and sedimentary rocks (Marlow and other,1973).The early series is believed by Marlow and others (1973),and Scholl and others (1975),and DeLong and others (1978)to be Eocene to middle ?- Miocene,53 to 15 m.y.old.The middle series or middle unit consists of plutons mainly granodiorite that have intruded the early series.These rocks have radiometric dates of 10 to 15 m.y.before present (Marlow and others,1973; DeLong and others,1978).The late series,which consists of basaltic and andesitic rocks that unconformablé overlie the early and middle series,is up to at least 3'm.y.in age,based on radiometric ages from andesitic magmas (Cameron and Stone,1970).Werwe Coarse pyroclastic and magma flow deposits found througout the northeastern part of Unalaska Island,mapped as the Unalaska Formation by Drewes et al. (1961),were found throughout the region southeast of Makushin Volcano (Plate I).The dacitic rocks of this formation were usually found to be tuffaceous ungraded breccia flows,whereas the andesites and basalts were represented by'magma and/or poorly graded breccia flows.These volcanic rocks grade into greenstones,having been altered by albitization,chloritization,epidotization, silicification,and zeolitization. The region immediately southeast of Makushin Volcano,including fumarole fields no.1,2,3,and 4 (Reeder,1982),consist mainly of rock exposures belonging to the Unalaska Formation which has been extensively intruded by Quartz monzodiorite and some gabbro (Plate I and II).Unaltered volcanics make up the Makushin volcanic pile and most of the rock exposures to the northwest of a line extending from Pakushin Cone to Table Top Mountain.Plutonic rocks were originally postulated by Drewes et al (1961)and later by Henning (Plate I)to suy aaunderliemostoftheseuna tered yvolcanics and a good part of Unalaska Island inpPoratkadndUndeConn t-ogeneral.Except for Pakushin Cone,the cones contained in the Makushin Volcano 4+Both the Pakushin and!= SZ:{region have been subjected to intense glacial erosion.Lo a:Wide Bay Cones,which lack intense glacial erosion,are suspected to have formed Peed el since the last glacial maximum which ended about 11,000 yrs ago (Black,1976).ae The line of cones trending toward Point Kadin (Figure 1)and the corresponding extruded lavas are believed by Drewes and others (1961)to have formed within the last several thousand years;they based their claim on the lack of glacial erosion on the cones and flows,and on the degree of development of a submarine bench at Point Kadin. ITI.Detailed structural geologic observations including gravity data,models, and interpretations. The contact boundaries between the Unalaska Formation and the intrusive bodies in the Makushin Volcano region appeared to be fairly complex.It was not unusual to find some of these contacts to be near vertical,and-it-was-not unustal to find small bodies of intrusive rock interfingering the highly altered Unalaska Formation (Plate II). Prominent near vertical joints have been observed striking roughly N60°E, N30°E,N55°W,and N8O0°W (Reeder,unpublished data)as shown on Plate II and on the equal area Schmidt net joint projections (Figure 1)for the northern part of Unalaska Island.In fact,the fumarole activity of fumaroles no.2 and no.3 appear to follow a near vertical N60°E joint system which roughly follows the immediate plutonic-metavolcanic contact boundary in these two areas. Near vertical faults having vertical displacements of between twenty feet to several hundred feet have been observed in the Makushin Volcano region (Reeder,1981 and 1982;Plate II).Most of these near vertical apparent normal faults strike N55-60°W,N35°E,and N85°E as indicated on the equal area Schmidt net fault projections (Figure 2).One of these N35°E faults trends directly into fumarole field no.5,and a N85°E fault trends directly through fumarole field no.1.Two N55°-60°W faults bound fumarole field no.2 as if they serve as impermeable boundaries,whereas one N55-60°W fault trends near fumarole field no.1 and another similar fault trends directly toward fumarole field no.5. Near vertical dikes of undetermined age have also been observed in the Makushin Volcano region,having strikes that are very similar to the previously mentioned faults (Reeder,unpublished data,Plate II,and Figure 3).Such porphry basaltic to dacitic dikes cut the Unalaska Formation throughout the northern part of Unalaska Island (Drewes et al.,1961;and Plate II).These dikes,striking dominantly between N40°W to N65°W and dipping steeply southwest, are numerous in the central part of Amaknak Island and in the Summer Bay region, making up in some places over 50%of the exposed rock.Such a concentration of dikes represent an ancient volcanic rift zone which probably supplied most of the volcanic materials making up the Unalaska Formation.A few porphyritic -4. dikes have been found cutting the plutonic rocks of the Captain's Bay region and of the Makushin Volcano region.Such dikes are geologically significant since they are younger than the Unalaska Formation and the plutonics that intrude this formation. | Lineations observed in the field and also from old World War II air photographs also appear to reflect the same directional trends as the observed dikes,faults,and even in a few cases,the observed joints (Reeder,unpublished data;Plate III,and Figure 4).In most cases where bedrock exposures have been good,all lineations have been found to reflect dikes and/or small faults.The lineation mapping,Plate III,will eventually be refined based on the high-quality air photographs obtained by North Pacific Aerial Surveys through Republic Geothermal,Inc.and the Alaska Power Authority. These fault and dike trends appear to fit into a regional fracture pattern that in part is predictable based on the regional compressional tectonic stresses due to the convergence of the Pacific Plate underneath the North American Plate (Nakamura et al.,1977;and Reeder,1981).The Aleutian arc is part of a ridge-trench system associated with active volcanism and seimicity. The Aleutian Trench is located about 180 km south of Unalaska Island.Global tectonics has the floor of the Pacific Ocean (the Pacific Plate)approaching the Aleutian arc (the North American Plate)in a northwesternly direction at a rate of about 7 cm/yr (Minster and others,1974),where the Pacific Plate at the Aleutian Trench is being thrusted under the North American Plate.This underthrusting causes compressional stresses in the direction of the plate convergence in the arc region.For Makushin Volcano,Nakamura et al.(1977) determined on the basis of orientation of flank eruptions,a maximum stress orientation of N55°W where the expected azimuth based on the direction of plate convergence should be about N45°W.Based on this regional maximum stress orientation,steeply dipping dikes and normal faults striking in a N55°W direction would be predicted to exist along with some dikes and normal faults striking perpendicular to this direction;i.e.,N35°E (Nakamura,1977).A few near vertical dikes and numerous strik-slip faults striking about N80°E and N10°W would also be predicted (Nakamura,1977).The only major deviation from this predicted pattern based on (fy)own field observations on Unalaska IslandP(Reeder,unpublished data;and Plate II)is that the N80°E observed faults -5- appear to be normal faults instead of the predicted strike-slip faults.The predicted N10°W faults appear to be lacking although dikes and lineations have been recognized as trending in this direction (Plate II and III,Figures 3 and 4). A total of 155 gravity reading:were obtained for the northern part of Unalaska Island during the summers of 1980 and 1982.The Complete Bouguer Anomaly Map resulting from the reduction of this data,using an average 2.6 gms/cc rock density for the terrain corrections,is shown on Plate IV.As shown,steep gravity gradients in a N50°W direction occur in the Beaver Inlet region and in the Makushin Bay region where very low gravity gradients occur in the Unalaska Bay and in the Shaisnikof Valley regions.In addition,large gravity anomaly lows occur in the upper Nateekin Valley and in the caldera region of Makushin Volcano,where a large gravity anomaly high occurs throughout the fumarole field no.1 through no.4 region and into a large region to the immediate southeast. Preliminary 2-dimensional gravity modelling along profiles Pro 040 and pro 135 as indicated on Plate IV has been recently undertaken.This modelling has been based on rock densities determined directly from rock samples (Table la,b, and c;and Plate V)and inversely for the less dense unaltered volcanics by fitting spherical models to the gravity data.As a result,it has been determined that the Unalaska Formation has an average density of about 2.77 in the immediate Unalaska community region but a density of as low as 2.60 in the Makushin Volcano region where it has been more highly altered and its tuffaceous units are more abundant.The plutonics have average densities as low as 2.59 for the granodiorite to 2.88 for the gabbros.The unaltered volcanics were determined to have densities of as high as 2.86 for individual basalt flows to an average density low of 2.0 for the fragmented materials within the Makushin Volcano Caldera and for cinder cones such as Sugarloaf and Table Top Mountain. The results of the preliminary gravity modelling after removing a regional gravity are shown in Figures 6 and 7.In general,the large gravity anomaly low in the Makushin Caldera region appears to be due to the existence of a fairly large volume of low density volcanic materials whereas the large gravity anomaly low in the upper Nateekin Valley is probably due to a large sedimentary sequence -6- of the Unalaska Formation.The low gravity anomaly that occupies the Unalaska Bay and the Shaisnikof Valley regions appears to be due to a large granodiorite body,whereas the high gravity anomalies in the Beaver Inlet region and the fumarole field no.8,1,2,and 3 region appear to be due to fairly dense quartz monzodiorite and/or gabbro bodies. Only a few aspects of this gravity modelling will be addressed which appear to have major significance toward better defining the structure and geothermal resources of this region.For example,the gravity modelling suggest that the dense monzodiorite body observed in the fumarole fields no.8,1,2,and 3 region does extend underneath the Makushin Volcano pile,along with probably some metavolcanics,until reaching a Makushin Volcano rift zone (Figure 7). This rift zone is oriented about N30°E and trends from Pakushin Cone through the southeastern part of Makushin Volcano caldera and down through the northwestern flank of Makushin Volcano between fumarole field no.7 and the first Republic Geothermal temperature-gradient hole (Figure 7 and Plate IV).Such a rift zone is also substantiated by geologic observations by Reeder (Plate II and an unpublished Recent Extrusions in the Makushin Volcano Region map).Based on the gravity data,this rift zone is about 3 km wide,where the dense quartz-monzodiorite continues on its other side underneath a fairly thick sequence of unaltered volcanics (Figure 7). Preliminary gravity modelling suggest that plutonic rocks in part intruded along steeply dipping bedding planes of the Uhalaska Formation in the region just southeast of fumarole field no.1.The Unalaska Formation has a regional strike to the northeast with usually a gentle dip (usually not more than 20°)to the northwest (Plate I).Detailed geologic observations indicate small deviations from this pattern such as represented by a small anticlinal fold trending northeast in the Captains Bay region and beds dipping by more than 45° to the northwest in the upper Nateekin Valley region (Plate II).Large meta- volcanic bodies that still retain their northeast strikes and their steep northwest dips appear to be nearly surrounded by intrusives as suggested by the gravity data.Some of the intrusive activity has probably followed weak bedding zones of the Unalaska Formation. The gravity modelling in the fumarole field no.l area depicts a large graben trending roughly east-west (Figure 6 and 7;and Plate IV)which has a depth of up to 2km and a width of only about lkm as represented by altered metavolcanics.The southern boundary of this structure would be marked by fumarole field no.1 and by the recognized N85°E fault which passes through this fumarole field (Plate II).The northern boundary would be marked roughly by the location of the Makushin Valley canyon and approximately by the location of the first Republic Geothermal temperature gradient hole.Another much narrower graben is suggested by the gravity data to parallel this one,where its southern boundary would overlap Sugarloaf Cone.Such structures trend directly into Makushin Volcano and also depict a similar trend of the lower Makushin Valley. IV.Petrographic and geochemical analyses of rocks. IV.A.Preliminary petrographic evaluation:The petrology and geochemistry of the volcanic rocks of the Makushin volcano region allow an evaluation of the extent and nature of volcanic activity at Makushin Volcano through time as well as help determine the character of any shallow magma systems.Such analysis extended to the plutonics and metavolcanics of this region could yield valuable insight into the nature of the country rock possibly being assimilated by intrusive bodies as well as insight into the history and present nature of hydrothermal activity. Quartz monzodiorite is the dominant rock type found in the intrusives near Makushin Volcano as based on model counts (Table 2)using the IUGS classification of igneous rocks (Streckeisin,1973),where some gabbros and quartz diorite are also present (Figure 8).Plagioclase was found to be the most abundant mineral,comprising more than 50%of the mode for all of the rocks.Subhedral augite,hypersthene,iron oxides,potassium feldspar,quartz, and biotite were usually always found in appreciable amounts in these rocks. In many of the samples,the plagioclase was found to be sericitized or albitized to some extent.Olivine was always found to be serpentized.In the more mafic intrusives,the augite phenocrystSare sub-ophitically intergrown with plagioclase phenocrysts Chlorite,epidote,and even clay minerals (suspected to be kaolinite)were recognized as secondary alteration minerals. The unaltered volcanics of the Unalaska volcano region;i.e.,the Makushin Volcanics,the Makushin Volcano Volcanics,and the Eider Point Volcanics (Plate Il),are predominantly basalt with subordinate amounts of andesite and pyroclastics and rarely some dacites.They typically contain less than 25% pheocryst of plagioclase and augite with smaller amounts of olivine, hypersthene,and/or more rarely horneblende (Table 2).Many of these rocks have been altered as indicated by the presence at several localities (other than in the fumarole fields which will be addressed later in this report)by silicifica- tion and zeolitization.Other more extensive alterations are strongly suspected and will be addressed as further petrographic examinations are undertaken. Geochemical evaluation:One hundred and four rock samples from the northern part of Unalaska Island have so far been analyzed for whole rock geochemical composition in the DGGS Fairbanks laboratory by means of X-ray fluorescence (XRF).The detailed results of the laboratory geochemical determinations are given in Table 3. High silica content volcanic rocks are usually indicative of volcanic regions which have or at least have had shallow magma chambers (i.e.,at depths of up to several kms).Also,because of the fine ground mass nature of most volcanic rocks,the whole rock analyses allow a positive identification of volcanic rocks.The silica content is the main basis of such a classification as follows:Basalt <52%;Basaltic andesite >52%but <56%;Andesite >56%but <62%;Dacite >62%but <67%;Rhyolites >67%. |All of the vapor-dominated hydrothermal systems that have been developed NAT AMR” into major sources of electrical power appear to be related to a rhyolitic heat oy te source.No rhyolites have so far been found in the Makushin Volcano region.no a oy The unaltered volcanic rocks of the Makushin Volcano region are predominantly oe basalt,where subordinate amounts of basaltic andesites and andesites have been found in the Sugarloaf Cone region,the Kadin Rift region,and the Pakushin Cone region.A fair amount of andesites and basalts make up the Makushin Volcano where subordinate amounts of dacite have been found at the summit of this volcano (63.3%Si0g)and on its southern flank (65%Si09).Hot dacitic bodies at shallow depths probably represent the best heat sources for driving hydrothermal systems in the region. The "dioritic"intrusive rocks exposed just east and southeast of Makushin Volcano range in silica contents of a Tow of 51%to as high as 62%.The highersilicacontentswerefoundintheGlacialValleyregionjustbelowfumarole _ fields no.3 and no.4;i.e.,not far from where the highest unaltered volcanic .° " a A .fos,.silica contents have been found.ook oo In order to evaluate the magma chamber(s)beneath Makushin,selected major and trace element analyses were carried out for spatially separated samples of a wide range in composition by Assistant Professor Charlie Langmuir at Lamont- Lamont-Doherty Geological Observatory.Sample locations are shown in Figure 9 -10- and Plate V.The coverage is of both the peripheral and central vents of the volcano. Separately prepared powders of rocks had previously been analyzed for major elements by X-ray fluoresence (Table 3).Lamont-Doherty analyzed for selected major elements to ensure that their analyses were comparable to ours.The SRF and plasma analyses are compared in Table 4.Agreement is very good considering that different portions of the rocks were crushed and different sample preparation techniques were used.The plasma analyses for MgO are consistently lower than the XRF analyses.In the figures,the plasma values were used. The major element analyses generally show smooth trends on variation diagrams.One example is shown in Figure 10.The observed trends are not dissimilar from any other volcanoes of convergent plate margins,and would seem to be consistent with a single mechanism of evolution for the entire volcano. The trace element analyses,however,reveal some complexities in the origins of the samples.Although there is a qualitatively continuous trend for most of the samples (Figures 11-13),in detail the variations are far more varied than can be accounted for simply by analytical uncertainty. The data become much less scattered when they are considered in terms of geographic location.Symbols for samples from the Table Top Mountain area have been filled in the diagrams,and they appear to be on separate trends from the rest of the data.They are relatively depleted in Ko0,La,and Ba,and relatively enriched in Sr.More important than the depletion in terms of over- all abundances are the differences in ratios such as K/La and Ba/La between the Table Top Mountain samples and the other samples.Such differences cannot easily be generated in a subvolcanic magma chamber,and most likely reflect deep seated differences inherited from the mantle source regions.This would strong- ly suggest that the Table Top Mountain volcanics are derived from a different magmatic plumbing system than the volcanics from the main Makushin cone. The three other samples,which are still from a large geographic area,may have been derived from a single evolving magma chamber.These samples show smooth variations on both major and trace element diagrams,and these variations are consistent with what would be expected from a magma chamber which is | -ll- cyrstallizing,and possibly assimilating material from the country rocks.The Mg0-Ti0g diagram suggests that Fe-Ti oxides became important in the crystallization process somewhere between 55 and 60%Si09.The gradually decreasing Sr content with increasing Si09 suggests that plagioclase was an important fractionating phase,which in turn requires the fractionation to occur at low to moderate pressures. Based on the work by Charlie Langmuir,volcanics from the Makushin Volcano region are not all derived from a single magmatic plumbing system.Those from the Table Top Mountain area seem to have been derived from a separate mantle source and to have undergone a separate evolutionary history.The Makushin Volcano region occurs in a transition zone separating oceanic and continental subduction domains as described by Kay,et al,(1982).Thus,having volcanics that have had a separate mantle source and have undergone a separate evolutionary history in the crust is consistent with Kay's model for the Aleutian Arc.Samples from the main Makushin cone may be related to a large magmatic system which has undergone extensive crystallization and assimilation over a significant period of time.The current hydrothermal and recent votcanic activity suggest that this system is still active. Potassium-argon age dating:Ten samples were submitted to Stan Evans of the Earth Science Laboratory,University of Utah Research Institute for potassium-argon age dating.Because of alteration coupled with the low potassium content,six of the samples were undateable (Letter 1).No absolute age determinations were possible from the remaining four samples because no radiogenic argon was detected from these "geologically"recent volcanic samples (Letter 2).Evans concluded,based on the detection limits of his age-dating equipment,that three of the samples are less than a half million years old and that one of the samples (U-G-27)is less than 50,000 years old.The U-G-27 sample is an andesite from near Sugarloaf Cone.The other samples are andesites from immediately above fumarole fields no.2 and no.3 and a basalt from a volcanic neck located between the Wide Bay Cone and Table Top Mountain. Additional age-dating attempts will be made from the Republic Geothermal ho.emtemperature-gradient cores,hy.pet L het. -12- IV.B.Hydrothermal alteration and clay mineralogy:Two major sources of hydrothermal alteration were identified in the vicinity of the Makushin Volcano. Extensive contact metamorphism is associated with the emplacement of granadiorite plutons within the older Unalaska terrain.Superimposed on this older alteration is a present cycle of hydrothermal alteration associated with fumaroles and hot springs driven by heat derived from the active Makushin Volcano.Samples collected during the 1982 field season from the greater Makushin Volcano Region included occurrences of both of these episodes of hydrothermal alteration.Samples were selected for routine petrographic examination in thin section as well as analyses by standard X-ray diffration techniques,where the results are given in Table 5.X-ray identification was utilized for the clay-size fraction material (<2 micron)which was separated by Stoke's law settling.The clay-size material was examined in both its natural and ethylene glycol-solvated conditions in order to distinguish swelling and non-swelling clays. Hydrothermal alteration associated with plutonic emplacement:Extensive iron staining and argillization have been observed by previous investigators in the major drainages surrounding the Makushin Volcano.This alteration is particularly obvious in the Makushin,Nateekin,and Glacier River Valleys.This alteration is associated with the granodiorite-Unalaska Formation contact and characteristically occurs as oxidation zones formed on sulfide-bearing tuffaceous rocks in direct contact with the granadiorite.Alteration locally has resulted in the conversion of a tuffaceous unit of the Unalaska Formation to a Brownish-cream clay.Because of its color and consistency,this tuffaceous unit was informally named "peanut butter"formation. Alteration products of the tuff,as observed in thin section,are dominantly sericite and chlorite.In the Nateekin Valley samples (N4 and N5), X-ray diffraction analyses indicate that the tuff is dominantly altered to illite,a clay-sized pottassium mica which would typically be identified as sericite by optical techniques.A distinctive feature of the Nateekin Valley samples and samples from contact zones of the same tuffaceous unit in Glacier Valley is the dominance of illite and the relative absence of zeolites such as clinoptillolite.The zeolites are commonly formed through lower temperature alteration processes.The sulfide-rich tuff (Sample No.N-7)from Glacier -13- Valley,as observed in thin section,displays extensive sericitization_and ,iron staining.Phenocrysts in tuff remain only as "ghost"outlines.The sulfide is dominant over pyrite,which occurs as 1 to 5 mm cubes.An assay of the pyritic tuff (Sample No.N-7)is included in Table 6. Hydrothermal alteration associated with Makushin Volcanics:The fumarolic fields on Makushin Volcano are characterized by an acid-alteration mineral assembly typical of the fumarole field driven by vapor-dominated geothermal systems.The general origin and association of kaolinite in the near surface has been described by White et al,(1971).Stfeam condensate made acid by its association with HoS is the actual mechanism which produces the alteration. As seen in thin section and field relationships,the largest fumarole field (#2) occurs in Makushin volcanic and Unalaska metavolcanic rock,probably andesites. Fresher samples closely associated with the extensively altered material contain cracked plagioclase phenocrysts with extensive rim sericitic and montmorillinitic alterations.Major minerals are extensively altered to "iddingsite,although some primary biotite remains.Gradation from a sample with most of the texture preserved (N-11)through samples with mixed montmorillinitic and kaolinitic alteration (N-10),to samples of relatively pure kaolinite (N-8)were observed.The joint-filling material is also dominantly kaolinite.Samples collected from the saddle in the divide between Makushin Valley and Glacier Valley reveal a pumiceous tuff which locally altered to kaolinic clay.The tuff is generally less altered than the andesite from fumarole #2 proper,which reflects a gap in the fumarole activity between fields #2 and #3 as well as the less reactive rhyodacite composition of the tuffs capping the divide. NaCl-bearing samples:Although the dominant surface expressions of hydrothermal activity on Makushin Volcano are characteristic of vapor-dominated systems,some direct and indirect evidence of recent hot spring activity was observed.Motyka located a remnant of kettle moraine in Glacier Valley,which is strongly cemented by Fe-oxides and clays.X-ray analysis of the clay-sized fraction of Sample N-1 revealed NaCl (halite)as a dominant constituent.In thin section,the andesite cobbles which comprise the moraine are observed to have been extensively hydrothermally altered to kaolinite and montmorillonite. -14- At a second site,a Makushin volcanic tuff was sampled just up-slope from drill site#2 (Sample N-2).The tuff was relatively fresh but halite waspresentin'clay-sized fraction.The same was collected near Fe-stained seep areas on the steep slope.Reeder_and.Henning also identified apparent warm spring seeps near the headwaters of Nateekin Valley.This evidence indicates the presence of local NaCl-rich waters within what is generally a vapor-dominated system developed on the slopes of Makushin Volcano. Conclusion to alteration and clay mineralogy evaluation:Care must be exercised when using hydrothermal alteration in the vicinity of the Makushin Volcano as a guide to geothermal well siting.Difficulties may be encountered in distinguishing between the extensive iron illite-rich alteration products related to plutonic emplacement as opposed to the less extensive kaolinite acid alteration products being formed today by fumarolic action on the flanks of the Volcano.The mapping of the Unalaska-dioritic contact zone was greatly facilitated by recognition of the distinctive reddish-brown to cream-colored alteration associated with it.The fumarolic alteration is more characteristically a more pink-to-cream colored zone and the differences are readily apparent once the distinction is recognized. The distribution of the alteration associated with the fumarolic activity on the flanks of the Volcano may be explained by at least two differing hypotheses or a combination of these two.The alteration and fumarolic activity may simply be localized at Makushin lava-Unalaska metavolcanic-diorite contact zones on the flank of the volcano with the contact zone providing the permeability for the stream migration.Alternatively,the alteration and fumarolic activity may be localized by fractures,joints,and faults which are obscured to a major extent by the alteration process acting on the relatively reactive basic lavas from the volcano.Significant relative displacements indicative of major faulting (i.e.,apparent relative displacements of fractions of kms or larger)were not observed within the fumarolic fields.However, lineations associated with the up-slope limits of fumarolic field #2 trending toward fumarolic fields #1 and #3 indicate that at least fracture patterns or joints may be responsible.The localization of the fumarolic activity by fracturing or some combination of fluid migration along contact zones and older fracture/joint patterns is the most probable factor in localizing the fumarolic fields.The distribution of the fumaroles and their associated alteration provides the most concrete evidence for the confirmed high temperature resource distribution in the vicinity of the Volcano. -15. V.Volcanic Hazard considerations A fairly thick sequence of pyroclastic deposits occur in three valleys in the Driftwood Bay and Makushin Volcano region.These deposits are thought to be related to a major eruption event of Makushin Volcano which resulted in the formation of the 3-km-dia summit caldera (Reeder,1982).Organic material was found underneath these pyroclastic materials and samples have been submitted to commercial laboratories for Cia age dating.Because these deposits overlie glacial tills,they are suspected to have been emplaced since the last glacial maximum which ended 11,000 years ago. | Since this eruption event,no major eruptions have occurred from the apie?caldera region of Makushin Volcano.It is highly suspected that the volcanicaie energy release activity of the caldera region is actually in equilibrium with 5 Kithelargeenergyreleasefromfumarolefieldno.6.If this is true,no majoraa? eruption events should be expected in the near future from the summit region of joan Makushin Volcano as long as fumarole field no.6 continues its activity.If such events did occur,there would probably be a fair number of large precursor earthquakes and other observable warnings. Flank eruptions especially on the northern flanks of Makushin Volcano could pose very serious volcanic hazards in the form of lava flows and heavy ash falls to any geothermal exploration and development activity.Such erputions have been quite common during "geologically recent"times (Reeder,unpublished data)and could occur with very little warning.Probably most of the historically recorded eruptions of Makushin Volcano were actually from flank eruptions occurring near fumarole field no.7. -16 TITLE -PROGRESS REPORT -THERMAL FLUID INVESTIGATIONS OF THE MAKUSHIN GEOTHERMAL AREA Authors:Roman J.Motyka Division of Geological and Geophysical Surveys Mary A.Moorman Division of Geological and Geophysical Surveys Robert Poreda Scripps Institute of Oceanography,University of California,LaJolla,California © KA \"Walmo Preliminary report submitted to the Alaska Power Authority in partial fulfillment of RSA number December 30,1982 This document has not received official DGGS review and publication status,and should not be quoted as such. This report on thermal fluid investigations at Makushin volcano consitutes section VI of the previously submitted report entitled "Makushin Volcano Geothermal Resources"by Reeder and others. -11- CONTENTS Progress Report---Thermal Fluid Investigations of the Makushin Geothermal Area Abstract Introduction Geologic Setting Thermal Areas Thermodynamic Implications of Superheated Fumarole Fumarolic Gases Gas Chemistry Stable Isotope Data Geothermometry Thermal Waters Water Chemistry General Features Makushin Valley Upper Glacier Valley,Gd Upper Glacier Valley,Ge-Gl Lower Glacier Valley,Cl-springs Geothermometry Stable Isotope Analysis of Waters Thermal Gradient Wells Model of Geothermal System Potential Drilling Sites Acknowledgements References Tables Figures -($- ABSTRACT Fumaroles discharging from the south and east flanks of Makushin Volcano are fed by a vapor-dominated zone associated with a hydrothermal system beneath the volcano.Observations support but do not confirm the existence of a vapor-dominated system at 235°C underlain by a hot-water reservoir.The host reservoir rock is the Makushin Pluton which is exposed at the heads of Glacier,Nateekin,and Makushin Valleys.Makushin volcanic flows act as a cap on the system and also help deflect rising fluids laterally outward to the exposed diorite.Based on thermodynamic considerations of a superheated fumarole and on bottom-hole temperatures in a thermal gradient well reservoir temperatures must exceed 190°C.as geothermometry suggests reservoir _ temperatures of 235°-300°C.The He/He compositions of gases withrespecttoatmosphericratiosrangefrom4.5 to 7.8;C compositons ofCO,range from -10,.2 to -13.0 Joo.These isotopic compositions indicate a magmatic influence on the geothermal system.The late-Pleistocene to Recent summit collapse caldera indicates the heat source is a shallow magma bodybeneathMakushinVolcano.The §D compositions of H,and steam from the superheated fumarole are near equilibrium for the ftimarole outlet temperature of 152°C.Isotopic composition of deep reggrvoir waters in equilibrium withthesuperheatedsteamisestimatedtobe4-0 -8 °/oo and §&D 80 to -86 foo.These isotopic values indicate meteoric waters that charge the deep system probably originate from the flanks of the composite volcano. Low Cl,HCO,-SO,thermal springs in Upper Glacier and Makushin Valleys originate from the circulation of local meteoric waters along fractures in the Makushin pluton and are isolated fron any deep hot-water reservoir.Depth of circulation in upper Glacier Valley must be#450 m.The waters are heated by steam and hot gases ascending from the deep reservoir and by conduction from wall-rock.Mg-rich Cl-springs.in lower Glacier Valley do not appear to be directly.related to a deep central hot-water reservoir beneath Makushin Volcano.The distribution of thermal springs,fumaroles,and heated ground in Glacier and Makushin Valleys suggests a subsidiary geothermal system exists along a northeast trending lineament east of Makushin Volcano. -\4- INTRODUCTION Unalaska Island,second largest in the arcuate chain of Aleutian Islands,is located between latitudes 53°15'and 54°N.and between longitudes 166°and 168°W.,200 km southwest of the Alaska Peninsula (fig.1).Umnalaska village lies on the southern shore of Illiuliuk Bay near the head of Unalaska Bay. The village has a permanent population of about 1,000 people. Because of the large and excellent deep-water harbor located at Unalaska Bay (one of the few protected harbors in the Aleutians),the village of Unalaska has naturally evolved into the major base of operations for the Bering Sea fishing industry.Thirteen fish processors operate in the area and bring in as many as 1,500 -2,000 seasonal employees during the height of crab-fishing season.Unalaska has the distinction of being the crab capital of the world. Unalaska will undoubtedly continue to grow.Recent offshore oil and gas exploration in the Bering Sea has already begun to tax the harbor facilities at Unalaska.The imminent entry of Alaskan fishermen into the Bering Sea bottom fishery will produce additional demands on the village. To help support its growing service industries,the village is actively seeking a dependable energy base.Electrical power needs of the village and the processors are presently met through oil-fired generators at a cost of 34¢ KwH.The area lacks any reasonable hydropower potential.As an alternative energy source DGGS began investigation of the geothermal energy potential of the surrounding area.Attention focused on Makushin Volcano located 20 km west of Unalaska Village (fig.1).Fumarole fields and thermal springs which occur on the flanks of the active volcano indicated the presence of a high-temperature geothermal resource that,if developed,could be used by the village.Geological and geophysical investigations of the area were initiated by J.Reeder of DGGS (Reeder,1982;Reeder,pers.comm.).Investigations of fluids associated with the thermal fields were undertaken by the authors to help assess the nature and extent of the underlying hydrothermal system,and to provide estimates of reservoir temperatures.The results of these earlier investigations indicated the presence of at least a shallow vapor dominated system located at the heads of Glacier and Makushin Valleys with gas geothermometry suggesting reservoir temperatures of 230 -280°C (Motyka and others ,1981;Motyka and others,1982). Based partially on the findings of DGGS studies and on economic and political factors,the state of Alaska funded a major exploratory drilling program at Makushin.The drilling program,under management by the Alaska Power Authority (APA),was initiated in 1982.Following an extensive selection process Republic Geothermal,Inc.(RGI),of California was chosen as the primary contractor.After conducting additional geophysical and geochemical investigations at Makushin Volcano,Republic Geothermal sited and drilled three 460 m (1,500 ft)thermal gradient holes during the summer of 1982,one of which had a measured bottom hole temperature of 195°C. In conjunction with the exploratory drilling phase,DGGS has cooperated and acted in an advisory capacity to both APA and RGI.In addition DGGS expanded its investigations of geothermal fluids associated with the Makushin geothermal area.The preliminary findings of these studies are the subject of this interim report.Details on geological and geophysical aspects are -Jdo- covered elsewhere (Reeder and others,1982;Republic Geothermal Report,in preparation,1982). As part of this expanded study,the authors have now sampled and are in the process of completing analysis of waters,gases,sinter deposits,and hydrothermal alteration products associated with most of the known thermal fields located on Makushin volcano,including the summit fumaroles.The data acquired thus far have helped further the understanding of the subsurface hydrothermal system and deep reservoir characteristics,reservoir temperatures,the source of volatiles in the system,the source of waters in the system,and geohydrological conditions.These data are also important in providing pre-exploitation baseline information on the geothermal resource. One vital purpose of these studies is to help guide the siting of the deep test well scheduled for the summer of 1983. The observations discussed below suggest a model of the Makushin geothermal system in which meteoric waters on the flanks of Makushin Volcano charge a deep hot-water reservoir where waters are heated by a cooling magma body.The geothermal waters boil at temperatures between 190°-235°C to form a vapor-dominated zone.Steam and gases ascending from this zone feed numerous fumaroles on the south and east flanks of the volcano and give rise to HCO,-SO,thermal springs. Q1- GEOLOGIC SETTING The Aleutian chain of active volcanoes lies immediately north of the Aleutian Trench,a convergent boundary between the North American and the Pacific lithospheric plates.This convergence produces one of the most seismically active belts in the world with much of the seismicity originating from the Benioff Zone,the subcrustal region where the Pacific plate is being actively subducted under the North American plate.The eruption of Aleutian magmas appears to be intimately related to this subduction process.The direction of motion of the North American plate is northwesterly.In the central Aleutians,this motion is nearly perpendicular to the strike of the volcanic arc with a rate of convergence of 6.6 cm/yr. The western part of the are has been built on oceanic crust that is younger than Cretaceous (Cooper and others,1974;Kay and others,1982),while the eastern part overlies the Mesozoic continental basement of the Alaska Peninsula (Reed and Lanphere,1973).Unalaska Island and Makushin Volcano lie on the transition zone separating oceanic and continental subduction domains. Generally the rocks that form the Aleutian Islands fall into three informal units as defined by Marlow and others,1973;Delong and others,1978;and summarized by Perfit and others (1980):(1)an "early series",as old as Eocene,composed of marine clastics,volcanoclastics and volcanic flows (predominatly submarine)and associated plutons that have been slightly deformed and metamorphosed to green schist-facies;(2)a middle unit of plutonic rocks with radiometric ages primarily between 10 and 15 m.y.b.p.3 and (3)a "late series"(¢5 m.y.b.p.)consisting of interbedded "andesitic" volcanic rocks and volcanoclastics that are unmetamorphosed and lie unconformably over the older units. On Unalaska Island,the Unalaska Formation constitutes the oldest and most extensive group of rocks on the island and consists of a thick sequence of coarse and fine sedimentary and pyroclastic rocks intercalated with dacitic, andesitic,and basaltic flows and sills,cut by numerous dikes and small plutons (Drewes and others,1961)(fig.2).The formation,which is exposed over two-thirds of the island,is at least as old as early Miocene (Perfit and others,1980)and is probably correlative with the "early series"occurring elsewhere in the Aleutians.The formation has been extensively folded, faulted,and intruded by plutonic rocks,with moderate hydrothermal alteration occurring near the plutons. Three well-exposed plutons,Captains Bay,Shaler,and Beaver Inlet,and several smaller plutons intrude the Unalaska Formation.Marlowe and others (1973)reported a K-Ar date of 11.1 +3.0 m.y.b.p.for the Shaler pluton; Lankford and Hill (1979)quote an unpublished K-Ar age of 13 m.y.(D.W. Scholl)for the Captain's Bay pluton.The chemistry of the plutons follow calc-alkaline trends (Kay and others,1982).The Captain's Bay pluton,which is typical of the larger granodiorite plutons along the arc,is crudely zoned from a narrow rim of two-pyroxene gabbro and diorite to a heterogeneous central region of hornblende-biotite granodiorite that is intruded by aplite dikes (Perfit and others,1980). Recent studies by Reeder and others (1982)on a pluton exposed at the heads of Makushin and Glacier Valleys suggest this intrusive is similar in composition to the Captain's Bay pluton.Chemical analyses on the Makushin intrusive Ja showed a ESE trend in silica content ranging from 51%in Makushin Valley to 62%in Glacier Valley with quartz monozo-diorite predominating.The age of this pluton is unknown but is probably correlative with intrusives elsewhere on Unalaska Island. The Makushin pluton is known to extend northward at least as far as W-1 (fig. 2)where it was encountered beneath 275 m (900')of volcanic flows ina thermal gradient well (C.Isselhardt,RGI,1982,pers.comm.).Preliminary interpretations of gravity data suggest the pluton dips to the northwest beneath Makushin Volcano at a moderately steep angle (Reeder and others, 1982).Most of the thermal activity observed at the surface on the flanks of Makushin Volcano occur within the exposed portion of this granodioritic intrusive. The western part of northern Unalaska is dominated by Makushin Volcano (2035 m),a major volcanic center in the Aleutian arc.The broad dome shaped summit has a small caldera and is capped by a glacier with tongues that descend the larger valleys to elevations as low as 300 m (2000 ft).Basalt and andesite flows and pyroclastic rocks from Makushin unconformably overlie the Unalaska formation and the plutonic rocks that intrude it (Drewes and others,1961).Marsh (1982)estimates the total volume of Makushin volcanicrocksat 200 km .Kay and others (1982)report the Makushin volcanic rocks have both tholefiitic and calc-alkaline affinities. Drewes and others (1961)estimated the onset of Makushin volcanism to be late Tertiary or Early Pleistocene,but that the bulk of the volcano was formed in the late Pleistocene.K-Ar determination of absolute age of volcanic rocks from the Makushin area submitted for analyses were not possible because of alteration problems with six of the samples and the apparent youth of the remaining four (J.Reeder,ADGGS,pers.comm.,1982).Based on the detection limits of the age-dating equipment used,three of the samples are considered to be younger than 0.5 m.y.b.p.and one sample is less than 50,000 m.y.b.p. (Stan Evans,ESL,U.of Utah,pers.comm.,1982). Four late Pleistocene to recent volcanic cinder cones and composite cones form a roughly NE-SW trend that cuts across the heads of Makushin and Glacier valleys.Recent whole rock and trace element analyses indicate that volcanic rocks at Wide Bay Cone and Table Top Mountain originated from a magmatic source separate from that associated with Makushin volcano (J.Reeder,ADDGS, and C.Langmuir,Lamount-Dougherty,pers.comm.,1982).Analysis of rocks from Sugarloaf and Pakushin cones appear to be compatible with a common magmatic source beneath Makushin. The lack of erosion of the caldera rim suggests the caldera formed in late Pleistocene or Recent times.Valley-filling pyroclastic flows and mud flow deposits occur at the head of Makushin Valley and in a valley south of Bishop Point.The flows may be related to the caldera forming eruption.In Makushin Valley these deposits form a flat uniform surface and overlie glacial till possibly deposited during a neoglacial advance. Makushin Volcano is still active and is known to have erupted at least 14 times since 1760,with a2 report of a minor eruption occurring in 1980 (Coats, 1950;SEAN,1980);Table Top Mountain has probably been active since the last major glaciation (Drewes and others,1961).,- -23- THERMAL AREAS The occurrence of active volcanic systems and shallow magmatically heated rock coupled with deep,penetrating fracture and fault systems caused by the caused by the convergence of two major lithosphere plates have provided a favorable setting for the development of hydrothermal systems throughout the Aleutian arc (Motyka,1982).At Makushin Volcano the surface expression of such hydrothermal systems are the numerous thermal springs and solfatara fields which occur on the east and southeast flanks of the mountain.Fumarolic activity and areas of geothermally heated ground have now been identified at 12 different locations on and near Makushin Volcano (fig.2).Eight of these sites (1-8)were found during previous field investigations (Maddren,1919; Drewes and others,19613;Motyka,Moorman,and Liss,1980;Motyka,Moorman and Poreda,19823;Reeder,1982);four additional sites (9-12)were found during the summer of 1982 (this report;M.Henning,ADGGS,pers.comm.,1982; P.Paramentier and C.Isselhardt,RGI,pers.comm.,1982).In addition, thermal springs are known to occur at 15 localities in Glacier Valley and its tributaries and in four localities at and near the head of Makushin Valley (fig.2).Several of these sites including the chloride springs Gm,Gn,and Gp in Glacier Valley,were discovered during the summer of 1982.Tables 1 and 2 provide brief descriptions and summarize key features of the thermal areas at Makushin.The number,variety,and distribution of thermal areas indicates the existence of a significant and widespread geothermal resource at Makushin. The most extensive regions of fumarolic activity on the flanks of Makushin Volcano occur at the heads of Makushin Valley (1,2 and 11)and Glacier Valley (3,4,and 9).These areas together with fumarole fields 5 and 7,form an arcuate zone of fumarolic activity on the eastern half of the mountain. Fumaroles on the flank of the volcano range in elevation from as low as 360 m (1)to as high as 870m (5).High pressure fumaroles were found at sites 3,4,5,and 6.One of these is a super-heated fumarole at 152°C,located near the upper end of site 3.Several vents at site 5 were slightly above boiling. High pressure fumaroles at the summit could not be measured because of ice hazards and noxious gases but are thought to be superheated. Numerous HCO.-SO,thermal springs occur in association with the fumarole fields at the heads of Glacier and Makushin Valleys.HCO,-SO,thermal springs also occur immediately down-valley from these fumarolic sites.Spring temperatures range from 40°C to boiling point.Warm Mg-Cl springs that are also rich in bicarbonate and sulfate are located along the west side of lower Glacier Valley.Spring Gp lies at an elevation of 100 m. Fumarole field 2 at the head of Makushin Valley and all fumaroles at the head of Glacier Valley lie at the eastern edge of the Makushin volcanic field and occur within the Makushin pluton.Thermal springs Ga through Gl and Ma and Mb also emanate from the diorite while spring Me occurs near the contact of Makushin volcanic rocks with the diorite.Although many of the fumaroles at these sites lie close to the contact with Makushin volcanic flows,the surface expression of fumarolic activity does not extend beyond the contact boundary. Surficial thermal activity appears to be largely controlled by the exposure of the Makushin pluton and the occurrence (or non-occurrence)of capping Makushin volcanic flows.The volcanic flows may also be deflecting fluids that ascend near the center of the volcano laterally outwards towards the exposed portions o- of the pluton.A tuff member located within the Unalaska formation appears to act as a cap on the eastern boundary of the Glacier and Makushin Valley thermal fields (M.Henning and C.Nichols,DGGS,pers.comm.,1982). Hot springs located in Glacier and Makushin Valleys together with thermal areas 1,2,3,8 and 12 appear to follow a roughly linear northeast trend, suggesting their distribution may be structurally controlled.The trend is coincident with a major lineament visible on vertical aerial photos and Landsat images and defined by Glacier Valley,the head of Makushin Valley,and a valley east of Driftwood Valley.Although some indication of faulting was found in diorite exposed near the head of Glacier Valley,no offset has yet been recognized along the trace of the lineament and the lineament does not appear to be fault related (M.Henning,DGGS,pers.comm.,1982).The lineament may reflect an older structural feature subsequently accentuated by glacier erosion.Glacier erosion is also probably responsible for exposing the pluton at the heads of Glacier and Makushin Valleys. Occurrence of hydrothermal alteration and relict fumarole vents on and within Recent moraines in Glacier Valley indicates thermal activity has been more extensive in the recent past.The moraines are probably correlative with a neo-glacial advance that occurred 3,000-4,000 y.b.p.elsewhere in the Aleutians (Black,1975).X-ray diffraction analysis of a sample of hydrothermal alteration obtained from fluvial deposits beneath a kettle moraine located south of Gj showed the presence of sodium chloride.The finding indicates that in the past chloride hot springs existed approximately 1 km north of the presently known chloride springs in Glacier Valley. 95- THERMODYNAMIC IMPLICATIONS OF SUPERHEATED FUMAROLE A superheated fumarole located near the top of fumarole field #3 (fig.2) measured 152°C during July,1982.The temperature measurement was made at the point of maximum vapor flow with a calibrated thermocouple accurate to +1°C. The location,geometry and heat of the vent prevented insertion of the probe more than 2-3 cm down the vent orifice.Another fumarole in the immediate vicinity,with much less pressure,measured 105°C.Meltwater flowing into this vent was obviously cooling the vapor.These superheated fumaroles at the head of Glacier Valley emanate from fractured and highly altered Makushin diorite near the base of a cliff consisting of capping Makushin volcanic flows. In natural geothermal systems the limiting process for the cooling of steam is adiabatic (isoenthalpic)decompression (Muffler and others,1982).The high temperature superheated fumarole at Glacier Valley thus provides a minimum estimate of 185-190°C for the parent saturated steam zone at depth (fig.3). The steam from the superheated fumarole is likely to have been cooled by liquid water,particularly near the surface,so that the saturated steam zone feeding the Glacier Valley fumaroles is probably higher than this minimum estimate.As a comparison,the temperature of steam decompressed adiabatically to a surface pressure of 1 bar abs.from saturated steam ofmaximumenthalpy(2,800 J g at 235°C and 31 bars abs.)is 163°C. High temperature superheated fumaroles are uncommon in geothermal systems. The highest temperature ever reported for a geothermal fumarole is 159°C, measured at Big Boiler fumarole during a period cf drought at the Lassen Volcano geothermal area (Muffler and others,1982).In addition to the superheated fumarole at the head of Glacier Valley at Makushin several high-pressure fumaroles occur on the south and southeast flank of the mountain (Table 1,sites 4 and 5).Although the fumaroles are at or near the boiling point,ground water flow.and observed surface water infiltration into the vents of these fumaroles wovld effectively quench any superheating. FUMAROLIC GASES With the exception of site 7,fumarole gas samples have now been obtained from every major fumarole field on Makushin Volcano including the summit.The gases were collected in one or both of two types of sampling flasks.Type 1 is an evacuated 50 ce glass flask with a vacuum stopcock.Type 2 is a 300 cc glass flask charged with 100 cc of 4 N NaOH solution which is then evacuated and closed with a vacuum stopcock.The sampling procedures are similar to those described by Giggenbach (1976)and by Nehring,Truesdell,and Janik (USGS,in preparation). Gas Chemistry Chemical compositions of gas samples analyzed thus far are given in Table 3 . Gases from sites 4 and back-up samples from sites 2,3,5,6,and 9 have not yet been analyzed.Analyses of the gases were performed in cooperation with the Stable Isotope Laboratory at the Scripps Institute of Oceanography at La Jolla,California and the USGS,Menlo Park,California.Results of the 1982 analyses are still preliminary and require further verification.The chemical compositions given for 3(f)and 6(h)are probably accurate to within +5 percent of the stated value.The compositions given for 5 (g)and 9(i)are more uncertain,particularly for HS,because of the gas chromatographset-up used for the analysis. Based on the present results the following observations can be made.Similar to other high-temperature geothermal systems the predominate gases at Makushin are CO,,N,,and H,S.Most if not all of the CO,and H,S is probably of magmatic origin.A significant amount of H,is also present, particularly at site 3 where H,is 1-2 percent of the total gas composition. The relatively greater percentage of H,and lower H,S found at site 3(d)probably reflects the loss of H,S throtigh rapid oxidation in shallow groundwatersandsurfacewaters.Reattion of H,S with dissolved 0,in these waters would result in the sulfate-rich acid-spring from which the sample was obtained. Concentrations of H,greater than 1 percent are commonly associated with high temperature geothermal systems,e.g.,Lassen (Muffler and others,1982); Yellowstone (Welhan,1981);Mt.Hood (Nehring and others,1982);and Cerro Prieto (Nehring and Valette-Silver,1982).H,in fumarolic gases may be derived from high-temperature interaction of water with ferrous-oxide silicates (Seward,1974).H,could also be of magmatic origin;H,is often a significant constituent of high-temperature superheated gases exsolved from recent volcanic vents,fresh lava flows and volcanic domes. The relative proportions of CH,in gases from Makushin are very low and the H,/CH,ratio is correspondingly high.Isotopic eviderice discussed later suggests the methane is not of magmatic origin.The CH,present in the gases could be derived from thermal decomposition of organic matter entrained in meteoric waters that charge the subsurface hydrothermal system.CH,could also be produced from the reaction CH,+2H,0 =co,+4H, (Giggenbach,1980). 3 17 The N,,Ar and 0,present in the gases are probably mostly of atmospheric origin as dissolVed gases in the recharge water.However,the high N,/Ar ratio for the five samples for which an Ar analysis is available suggests some of the N,may have a different origin.The N,/Ar ratio is 84 for air and 37 for air-saturated water (Mazor and Wasserberg,1965)compared to a N,/Ar ratio of 115 for 2(c),101 for 3(e)and 98 for 2(b).The excess Ny could beofamagmaticorigin. Preliminary analyses of NH,content of gases from two sites,3(f)and 6(h), indicate concentrations on the order of 50 ppm.The NH,present in thesystemcouldbeproducedthroughthereaction 2NH,=No +3H, (Giggenbach,1980). The CO,/H,S ratio is lowest for the superheated fumarole 3(f).The ratioofCO,7H g will increase with decreasing temperature in geothermalsystemsBecauseH,S is selectively removed by water-rock interactions to form Pyrite (Truesdell and Thompson,1982).H,S can also be removed by reaction with dissolved 0,in ground waters and surface waters through which the gases pass.The gas analyses for 3 (f)is thus likely to be the most representative of gas composition of the deep reservoir. Stable Isotope Data 3He/*He:In cooperation with the Stable Isotope Laboratory at the Scripps Institute of Oceanography (SIO),LaJolla,California,samples of gases obtained from fumaroles and hot springs of,Makushin have been analyzed for their He isotope content.Enrichments in He WRT to atmospheric levels have een correlated with magmatic activity on a world-wide basis with the excessHethoughttgbe,derived from the mantle (Craig and Lupton,1981).Samples of gases for He/He were collected from Makushin sites using 50 ce 1720 (Corning)glass flasks fitted with high-vacuum stop-cocks.The procedures followed for gas extraction,,measurement of absolute helium amounts,massspectrometermeasurementof He/He ratios and application of He/Ne correction for air contamination are described in Lupton and Craig,1975 and Torgersen and others,1982, Table 4 presents He isotope data thus far acquired for the Makushin sites. The valyes are given in terms of ratios with respect to atmospheric levelswithR="He/He of the gas sample and Ra = He/He atmospheric.The R/Ra value of 7.8 obtained for the summit vent falls within the range of values,6 to 8,obtained from other volcanic vents in the Aleutian arc and from convergent margin volcanic arc settings elsewhere in the world (Craig and others,1978;Poreda,Craig,and Motyka,1981;Poreda and Motyka,unpublished data,1982).R/Ra values for gases from fumaroles on the flanks of Makushin are all lower than the summit with the lowest values,4.5,occurring in Glacier Valley. Such variations in R/Ra have been found at other volcanically related geothermal systems (Torgersen and others,1982;Torgerson and Jenkins,1982; Welhan,1981).A high value for R/Ra in gases from geothermal systems suggests a more direct connection to magmatic sources with little crustal 16- contamination although it may also result from leaching of young volcanic rock (Truesdell and Hulston,1980).Lower values indicate a greater crustal influence of radiogenic 'He. If the summit value of R/Ra is taken to represent the He ratio of the parent cooling magma,then the R/Ra values for sites on the flanks of the volcano represent varying degrees of mixing with a crustal component.One effective method for increasing the amount of He present in the gases is by hot water interaction and leaching of reservoir wall-rock.At Makushin the host reservoir rock appears to be a diorite pluton.Calculations by Torgersen and Jenkins (1982)indicate the R/Ra ratio in a diorite such as that at Makushin would fall tog0.1 through radiogenic decay of U and Th for emplacement ages 21.0 m.y.A mixing of 40 percent crustal He and 60 percent magmatic He would produce a R/Ra ratio of 4.5 using 7.8 for the magmatic component and 0.1 for the crustal component. 136/126 and D/H:The authors'study of 136/12 and D/H ratios at Makushin and elsewhere in the Aleutian arc are still in their initial stages. The analyses of the stable isotopes of C and H,found in geothermal gases and waters are useful for deciphering the origin of gases in the geothermalsystem.Fractionation of the C isotopes between CO,,CH,,and HCO and the D isotope between HAO,Hy»and CH,has also beén used to inferreservoirtemperatures, Preliminary results for sites at Makushin analyzed thus far are given in tables 5 and 6.Methods used for extracting the C gases and H,and analyzing them for stable isotopic composition are described in Welhan (1981), Nehring,Truesdell,and Janik (USGS,in preparation)and Lyon and Truesdell (USGS,in preparation).The isotopic values are given in terms of relativedifferencesexpressedinpartsperthousand(permil,or °/oo)and defined as gx =(z )10°(1)| Rstd where Rx represents the isotope ratio of a sample and Rstq is,the corres-ponding ratio in a standard.For C,the standard is the C/"C ratio in a limestone termed "PDB"(Fritz and Fontes,1980).For H,the standard is the D/H ratio in Standard Mean Ocean Water (SMOW)defined by Craig (1961). The three §+3¢-co analyses by Global Geochem,Inc.,were done on co,gas evolved from a SrCO,precipitate.The SrCO,precipitates wereobtainedfromNaOHsolutionscontainedintype3samplingflasksaccording to procedures described in Nehring,Truesdell,and Janik (USGS,in preparation).The single SIO analysis of §° C-CO,was performed on unreacted CO gasextractedfromatype1samplingflask.The three CO,samples analyzed byGlobalGeochem,Inc.,are lighter by w 2 °foo than thé single sample analyzed by SIO.Additional samples from these and other sites at Makushin are ing submitted to a third laboratory to determine whether the differences in C are due to differing lab procedures or whether the values in Table 5 represent actual variations in isotopic composition of co,at Makushin. The $136 compositions of ce from Makushin are compared in fig.4 withcarbonisotopedatafromothergeothermalareas.The Makushin CO,appears generally lighter than most of the other geothermal areas shown."The Makushin - 29- CO,however is only slightly lighter than CO pqnalyzed from the Akutan andAtageothermalareasintheAleutianarc.z C -CO,ranges from -9 to"fh /oo at Atka and is 10%at Akutan (Motyka,unpublished data,1982).C of "juvenile"or mantle derived CO,is thought to range from -4 to-8 °/oo (Craig,1953;Welhan,1981).This range is based on analyses of samples obtained from mid-ocean ridges and from carbonatites and diamonds. Subduction related magmas however may become contaminated by volatiles from th down-going slab or by,incorporation of crustal material thus changing theSC-CO,.Analysis of S° c-co fromthe summit of Makushin mayprovideanestimatefor"magmatic"$ C-CO,at Makushin.This value in turn will allow a better evaluation of the source(s)of co,in the Makushingeothermalsystem.. Except for the summit,the volume of CH,contained in the samples from Mekushin analyzed thus far have been too low to allow determination of5 C-CH,and §D-CH,.The CH,in the sample from Site 3,GV-1,.,thesuperheatedfumarole,was barely at the detection limit for 9 C and the range of values are included in Table 5 only as a suggestion of what theC-CH,might be for Site 3.Welhan (1981)has presented evidence for CH derived from a mantle source along the East-Pacific Rise.The $3 o-cH for this abiogenic methane ranged from -15.0 to -17.6 /oo. Methane from the summit and flank of Makushin is considerably lighter and is probably derived mostly from the thermogenic breakdown of organic matter. The §D compositions of H,and CH,from Makushin are compared in fig 6 to other geothermal systems and volcanic vents.Fractionation can occur between any of the hydrogen containing gases (H,,CH,,H,S,NH,)and H,O but H,O (liquid and vapor)is usually present in such great abundance that it probably controls the D isotopic fractionation behavior of the other constituents.The fractionation of D between H,and H,O is very rapid and H,-H,0 is commonly found to be at or near isotopic equilibrium for the outlet temperature of fumarolic vents and geothermal wells.Kiyosu (1982), however,has recently reported that at several high-temperature fumarolic vents in Japan the §D in H,-H O(v)indicated isotopic equilibrium100-200°C higher than the Suttet temperatures.At the Makushin superheatedfumarole$D in H,and H,0(v)(see table 9)appears to be nearly inequilibriumforthemeasuredorificetemperaturesasdiscussedbelow.The equilibrium temperature for D in H,and H,O (V)for the summit fumarolesampledisconsiderablybelowtheoutlettemperature.The steam in this vent may be of local meltwater origin and may not have come to equilibriun. The single §D-CH,available for Makushin,obtained from the summit,is heavier in D than most other reported sites.The §D-CH,may be inherited from organic matter.Experimental data for D in the system CH -H,0 arestilllackingandthesignificanceoftheMakushinsummit5p-ch,Is not yetapparent. -30- Geothermometry D'Amore and Panichi (1980)have proposed a gas geothermometer for estimating reservoir temperatures that is based on the proportions of CO,,H.S,H., and CH,measured at a geothermal vent.The geothermometer temperature is calculated using an empirical relationship derived from examining the composition of 42 gas samples and measured reservoir temperatures from a variety of explored geothermal areas.The uncertainty of the calculatedvs. observed temperatures is +13 percent.Only 14 of the samples used to derive the relationship were from natural manifestations;the rest were from geothermal wells.Muffler and others (1982),however,found reasonable agreement between temperatures predicted by Na-K,Na-K-Ca,and sulfate-water oxygen isotope geothermometers for Growler Hot Spring waters and the gas geothermometer of D'Amore and Panichi for gases from fumaroles and hot springs in Lassen Volcano National Park and vicinity. The results of applying the gas geothermometer to the Makushin area are given in Table 7.The deep temperature estimates range from 230°C to 297°C.The temperature estimates overlap within the limits of calculation uncertainty. Because the gas constituents used in the geothermometer can be affected by near-surface water-rock reactions,the gas geothermometer is best applied to fumaroles and springs that have high gas flow rates and for which the gases are not in contact with a large,low-temperature water table (D'Amore and Panichi,1980).Based on this criteria,the superheated fumarole geothermometer temperature of 297°C would then be the most dependable estimate for the deep reservoir.Two of the other analyses (#2C and #3,acid spring) also give temperatures greater than 280°C. The deep temperature estimates of 280 -300°C are significantly higher than the minimum estimate provided by thermodynamic considerations of the superheated fumarole (2190°C)and the highest temperature encountered in the thermal gradient wells drilled during the summer,1982 (195°C,W-2,see below; P.Parmentier,RGI,written communication,1982).The temperatures are also well above the 235-240°C normally found in deep vapor-dominated reservoirs. Because of the uncertainties of the geothermometry calculations and the preliminary nature of the gas analysis data,particularly for the superheated fumarole,any discussion on the significance of the gas geothermometry must be speculative:1)The gases may be equilibrating in a vapor-dominated reservoir and the geothermometry has overestimated the temperature of equilibration;2)The gases may be equilibrating in a hot-water reservoir of 280-300°C underlying a vapor-dominated reservoir at 235-240°C;3)The gases may be equilibrating in a hot-water reservoir at 280-300°C in which boiling and steam separation occurs at temperatures %190°C;4)The deep system is "dry"(i.e.,no liquid water)at temperatures 280-300°C.In the latter case surface waters infiltrating the fractured dioritic pluton would react with and be vaporized by superheated gases and hot dry rock.From the standpoint of development of geothermal energy the latter possibility is by far the least desirable. Fractionation of the 13,isotope between CO,and CH,has been used as a geothermometer based on the assumption the gases are in isotopic equilibrium through the exchange reaction:: 2 2 2CO,+4H,=CH,+2H 3\- Craig's (1953)calculations of the temperature dependence of 136 fractionation between CO,and CH,were subsequently modified by Bottinga (1969).Geothermometric temperatures calculated using Bottinga's fractionation curve,however,were found to be significantly higher than observed system temperatures which cast doubt on the validity of the geothermometer (Truesdell and Hulston,1980).Gunter and Musgrave (1971) suggested that isotopic equilibrium is not established and investigations by Des Marais and others (1981)indicated that methane in geothermal systems is formed by the thermal decomposition of organic matter,not by the reaction of H,with CO,.2 2 Others suggested the isotopic temperatures are real but occur in deeper parts of the system (Panichi and others,19773;Hulston,1977).This hypothesis was reinforced by the discovery of higher temperatures (>300°C)in deep research drill holes 'at Lardello and at Broadlands (Truesdell and Hulston,1980). Application of this geothermometer,however,remains controversial, particularly for temperatyres below 400°C where experimental and theoreticalinvestigationsindicate""C equilibration requires residence times on the order of tens of thousands of years (Sackett and Chung,1979;Giggenbach, 1982). Available 136 analyses of coexisting CO,and CH,in geothermal gases,as well as some analyses of low-temperature gases with indicated isotopic temperatures,are shown,in fig.6.Makushin data is also plotted forcomparison.Using a §° C value of -31 for CH,and -10.2 for co,givesanisotopeequilibrationtemperatureof360°C for Makushin. The §D values of coexisting H,and H,O have also been used as geothermometers based on the aSsumption that the gases are in isotopic equilibrium through the reaction H,O +HD =HDO +H, As discussed above,isotopic fractionation of D occurs rapidly and application of the 9D,H,-H,O geothermometer to geothermal systems has shown variable degrees of re-equilibration between the reservoir and the sampling point (Truesdell and Hulston,1980).The fractionation factor,,over the range 273-473°K can be expressed as: In<=-0.2735 +499.2/T +2280/T*(2) where T is the absolute temperature and X =1000 +D (H,)(3) 1000 +D (HZ0)(Richet and others,1979;Rolson and others,1976).Applying these equations to the superheated fumarole of Makushin gives an equilibration temperature of 157°C which is slightly above the measured outlet temperature. -323- THERMAL WATERS Locations,descriptions and physical characteristics of thermal springs identified in the Makushin area are summarized in Table 2 abd fig.2. Water Chemistry Fifteen thermal springs and five cold waters located in Glacier and Makushin Valleys were sampled and analyzed for major and minor chemical constituents. The results of these analyses are given in Tables 8,9,10,and ll.Ata majority of the sites,sampling procedures followed those described in Presser and Barnes (1974).Bicarbonate and pH were determined in the field using methods described by Barnes (1964).For several sites (analyses #1,3,7,11, and 19)lack of time prevented following rigorous field sampling procedures and analyses were performed on unfiltered,untreated waters.All samples were analyzed at the Geothermal Fluids Laboratory of DGGS.Descriptions of the analytical methods used and their precisions are found in Motyka,Moorman,and Liss (1981).Anion-Cation balances for the majority of the samples for which a field determination of bicarbonate was performed are<¢5%.The balance for one cold water sample (analyses #6)exceeded 25 percent and is probably attributable to the very low concentration of dissolved solids in the sample. The percentage cation and anion contents of the thermal waters and cold waters are plotted on trilateral diagrams in figs.7 and 8.These "Piper"diagrams are useful for classifying and grouping water types and determining similarities,relationships and trends in water chemistry.The bicarbonate percentages plotted for analyses 1,3,7,11 and 19 were determined by calculating the amount of bicarbonate needed to balance anions with cations. General Features Most of the thermal springs are near-neutral in pH although acid springs also occur,usually near fumarolic vents.All of the near-neutral pH thermal springs sampled in Glacier and Makushin Valleys have significant concentrations of HCO,and SO,and all except Gn,Gm,and Gp are very lowinCl(<10ppm).Acid springs'and HCO,-SO,rich thermal waters that are low in Cl are commonly associated with vapor-dominated systems (White and others,1971)and are often found on the flanks of active volcanoes. Vapor-dominated systems have been identified or are thought to exist at several convergent margin volcanoes (Oki and Hirano,1970;Mahon and others, 1980;Muffler and others,1982).The HCO,and SO,contents of thermal waters in Makushin Valley and upper Glacier Valley are probably derived from oxidation and reaction of ascending H,S and co,gases with ground waters. Cations in the thermal waters are primarily Ca and Na with Ca usually predominating.Thermal springs in the upper Glacier Valley are particularly rich in Ca and several springs are depositing CaCO,at the surface.Mg and K are present in subordinate amounts.The cations in the thermal waters probably originate from the interaction of warm waters with the diorite host rock.C0O,-rich waters at elevated temperatures can readily leach calcic feldspars in the diorite to produce clay minerals,bicarbonate,and Ca and alkali ions (Truesdell,1976;D.Hawkins,U.of Alaska,personal communication), -33- cO,+H,O +(Ca,Na,K)silicate =HCO92 +(Cat,Nat,K+)+H silicate3 The concentrationof Mg in the springs is particularly significant because it indicates that water-rock reactions have occurred at relatively low tempera- tures.With increasing temperatures Mg is usually removed through chlorite alteration reactions. All the thermal springs have significant concentrations of Si0,,usually%100 ppm.The high SiO,may reflect equilibration of waters with quartz or chalcedony,or possibly leaching of SiO,from silicates in the country rock by CO,-rich waters (D.Hawkins,University of Alaska,pers.comm.,1982).Numerous Mg-rich low-temperature soda-springs saturated with respect to | amorphous SiO,occur in California.The SiO,in these waters is thought to be derived from the low-temperature interaction of cO,-rich waters withserpentinite(Barnes and others,1981). The thermal springs of Makushin appear to fall into several distinctive groups based on chemistry and location.These divisions are discernable on the cation piper diagram (fig.7)as 1)Makushin Valley;2)Upper Glacier Valley, springs Gd;3)Upper Glacier Valley,springs Ge-Gl;and 4)Lower Glacier Valley,springs Gm-Gp. Makushin Valley The four thermal springs sampled in Makushin Valley have lower concentrations of dissolved solids,lower pH and generally lower flow rates compared to most of the springs found in Glacier Valley.Cation concentrations in the Makushin Valley thermal waters occur in roughly similar proportions with the ratios of Ca/Na ranging from 1 to 2.5.The cation proportions in fact are very similar to three of the cold waters sampled in the Makushin area.These cold waters, two of which are streams (7 and 19)and one of which was a snow melt spring, had very low concentrations of dissolved solids.Anion proportions in the Makushin thermal springs are similar to each other but differ from the cold waters. Thermal springs in Makushin Valley are much fewer in number than Glacier Valley and usually occur in close association with fumarolic activity.Rock cores obtained from thermal gradient holes show much less fracturing at shallow levels in Makushin Valley than Glacier Valley.The opportunity for circulation of ground waters and formation of thermal springs would thus be more limited in Makushin Valley.Also,the upper part of Makushin Valley has been inundated with a Recent debris flow which may have buried and masked thermal springs at lower elevations. The similarity in cation proportions to local cold waters,the low Cl and high HCO.-SO,concentrations,and the proximity to active fumaroles all indicate the Makushin Valley thermal springs originate as local meteoric waters circulating along fractures,subsequently heated by condensing steam and hot gases.The relatively low concentration of dissolved solids in the thermal waters suggests shallow circulation and rapid flow of the waters through the country rock. Upper Glacier Valley,Gd 34- The three springs sampled at site Gd are within 100 m of each other but show marked variations in TDS,.HCO,and SO,.The springs are located at the base of fumarole field 3 and the variations are probably a function of interaction with fumarolic gases and depth from which the individual spring waters ascend.The springs at Gd are similar in their cation concentration and are distinguished from other springs further down Glacier Valley by their much lower Ca/Na ratios.The low concentration of Ca at Gd suggests depths of circulation at Gd are shallower than elsewhere in Glacier Valley.As at Makushin Valley,the springs at Gd probably originate from the near-surface mixing and interaction of ground waters with steam and hot gases. Upper Glacier Valley,Ge-Gl Six groups of thermal springs (Ge-Gj)occur in a canyon located near the head of Glacier Valley,below fumarole field 3 (table 2;fig.2).The springs cover a distance of about 1/2 km and emanate from colluvium and glacial till at the base of the canyon walls and along stream channels.Local bedrock is highly fractured Makushin pluton.Each spring group consists of several vents.Discharge averages about 50 lpm per group;temperatures range from 40-80°C. Hot springs also occur in a western tributary valley to Glacier Valley (Gk and G1)below fumarole fields 4 and 9.Site Gl consists of numerous spring vents covering a distance of 100 m along a stream channel.Total flow is about 350 lpm and temperatures range from 50-63°C. The hot springs sampled have very similar chemical compositions (Table 10). The TDS is over twice the amount found at Gd and in Makushin Valley.Most of the increased TDS is due to higher concentrations of Ca,HCO,,and SO,-All the spring groups sampled are saturated in Ca and HCO,afd are depositing calcite at the surface.One spring at Gd has Constructed amulti-hued calcite cone about 1 meter in diameter. The thermal springs plot in a tight group on both the cation and anion diagrams (figs.7 and 8)indicating the springs have a similar origin or perhaps are derived from a common parent reservoir.The thermal springs are also similar in cation proportions to two cold springs sampled in the immediate vicinity (analyses 20 and 21).Waters from these cold springs, which are much higher in TDS than the other cold waters sampled,are apparently circulating along fractures in the diorite but at much shallower levels than the thermal springs. Thermal gradient well W-3 drilled near Gj intersected a zone of rapidly increasing temperatures and artesian flow at a depth of about 70 m (fig 10) (P.Parmentier and C.Isselhardt,RGI,pers.comm.,1982).Temperatures at the base of this zone measured 45°C while bottomhole temperature at 460 m was 78°C.This temperature range is similar to that measured for the thermal springs in the area.The temperature profile for W-3 suggests warm waters are convecting from depths of 450 m and deeper and mixing with colder ground waters at shallower depths to produce the thermal springs at.the surface. The low Cl content,high HCO and $O,,the association with fumarole fields,and the similarity in cation proportions to local cold ground waters indicate the thermal waters originate from the interaction of infiltrating 35- meteoric waters with rising steam and gases from a vapor-dominated zone.The depth of circulation and reservoir residence time of the thermal waters at Glacier Valley must be greater than at Makushin Valley to account for the increased concentrations of Ca,HCO,and SO,.Based on drilling evidence, the depth of this circulation appears to exceed 450 m. Lower Glacier Valley,Cl-springs Three Cl-rich thermal springs are found in the lower portions of Glacier Valley (fig.2).Two of the springs,Gm and Gn,occur at and near the mouth of a western tributary valley;spring Gp lies north of the mouth of Pakushin Valley.Spring Gm is located near the contact between the Makushin pluton and the overlying Unalaska Formation.Exposures of diorite down-valley of Gm are reported by Henning and Reeder (1982).Bedrock exposed above Gp is Unalaska Formation.All three springs have low discharge (20 Ipm)and moderate temperatures (30-40°C). The chemical compositions of Gm and Gn are similar (Table 10)and the two springs plot closely together on both cation and anion diagrams (fig.7 and 8),suggesting the two spring waters are related to the same source.Waters from Gp are more enriched in Na,Cl,and HCO,compared to Gm and Gn.The similarity in ratio of the conservative eleménts C1/B,however,suggests the thermal waters at Gp are related to Gm and Gn or perhaps originate through similar chemical processes.The high concentration of Mg at all three sites suggest the waters originate from a low temperature environment or by mixing of hotter waters with cold waters near the surface. Compared to the thermal springs in Upper Glacier Valley,sites Gm,Gn,and Gp are significantly enriched in Na,K,Mg,HCO,and Cl.In fact,there appears to be a down-valley trend of enrichmént of these constituents accompanied by a depletion of Ca and SO,.The depletion in Ca and SOsuggestspossibledepositionofgypsumoranhydritebeneaththelower part of Glacier Valley. The origin of the constituents in the lower Glacier Valley thermal waters is not yet clear.Three possibilities are suggested for the origins of the Mg-rich Cl-springs.1).A portion of the waters originate from a Na-Cl hot-water reservoir associated with the Makushin Volcano geothermal resource. These waters cool upon ascent and become diluted with colder ground waters. The low temperature mixed-water then dissolves Mg from the shallow reservoir before emerging as springs.2).Cli-poor thermal waters,similar in origin to springs in upper Glacier Valley,circulate through rocks of the Unalaska Formation where Na,K,Cl and Mg are leached from submarine deposited volcanoclastics and flows.3)Local meteoric waters circulate to moderate depths along fractures associated with local faults where they are heated by conduction from the country rock.The regional thermal gradient would be assumed to be high in the vicinity of active volcanism. The Cl and B content of these springs,if derived from a deep Na-Cl hot-water reservoir,indicates the fraction of hot water should be over twice as great at Gp than at Gm and Gn.Such mixing,however,is not reflected in the temperatures of the springs nor in the SiO,concentrations.Isotopicevidencediscussedbelowalsosuggeststhatthethermalwatersarenot derived from a single deep hot-water reservoir. -3b67 The thermal waters do not resemble any of the cold waters sampled at the heads of Glacier and Makushin Valleys.Cold waters that circulate through rocks of the Unalaska Formation have not yet been sampled.The thickness of the Unalaska Formation overlying the diorite appears to increase down-valley. Thermal waters further down-valley would therefore have to migrate through greater thicknesses of the formation.The thermal springs Gp lie near the major fault in Pakushin Valley.The springs at Gm and Gn are close to the contact between the Makushin pluton and Unalaska Formation and lie near the projection of a fault mapped on the east side of the valley.The high concentrations of HCO,and SO,in these spring waters indicate extensiveinteracticnwithCO,and H,S.°The chemical trends observed in the GlacierValleySprings,the high HCO - SO,concentrations,the association of the springs with faults and the apparent down-valley increase in thickness of the Unalaska Formation would favor either possibilities 2)or 3)or both. Geothermometry Results of applying SiO,and cation geothermometers to representativethermalwatersatMakushinaregiveninTable12.Because of the ambiguities associated with the origins of the chemical constituents in these waters the geothermometers are of questionable value.Quartz does occur in the Makushin pluton and chalcedony has been identified in fractures present in rock cores removed from the thermal gradient wells.The SiO,geothermometer could therefore reflect equilibration with either of thése SiO,phases.However, as noted before,the SiO,present in the waters could have also been introduced by dissolution of feldspars by CO,-rich waters or by acid-leaching and dissolution of country rock.The waters,however,are undersaturated in amorphous silica with respect to the outlet spring temperatures. A similarly ambiguous situation occurs with the cation geothermometers.TheNa/K geothermometers predict high temperatures whereas,using Fournier and Truesdell's (1973)criteria,the calcium corrected cation thermometer gives temperatures lower than the outlet temperatures for Gf and Gh and well below the SiO,predicted temperatures for Mc,Gf,Gh and Gm.Residence time of the thermal waters may have been too short for cation equilibrium to occur. Ambiguities also occur at the Cl-spring Gp.The (1/3)Na-K-Ca gives a temperature of 175°C,but application of a Mg correction,suggested by Fournier and Potter (1978)drops the predicted temperature to 70°C.Use of the Mg correction,however,depends on whether the Mg is introduced through near-surface mixing or whether it is a property of the deep thermal water itself,a situation which is not yet resolvable at Gp.Such ambiguities and the general discordance between the various geothermometers underscore the need to treat the thermal water geothermometers with caution. Stable Isotope Analysis of Waters Samples of thermal waters,steam condensates,and locally derived meteoric yaters (LDMW)obtained from Makushin have been analyzed for ratios ofO/--O and D/H (Table 13;fig.9).Stable isotope analyses of geothermal waters have proved useful for identifying the sources of waters in the geothermal system,estimating mixing with non-thermal waters and estimating the degree of water-rock interactions within the reservoir.A review of the -37- application of water isotope studies for geothermal systems can be found in Truesdell and Hulston (1980).The isotopic values in Table 13 are given in terms of relative differences,as defined by equation (1),with Fgspect toStandardMeanOceanWater(SMOW)defiend by Craig (1961).All $O and §D analyses were performed by Dr.R.Harmon either at the Scottish Universities Reactor Centre,Glasgow,Scotland (1980 and 1981 analyses)or at the Stable Isotope Laboratory at Southern Methodist University,Houston,Texas (1982analysgs).The reported precisions are 1.0 °foo for §D and 0.2 foofor6-0. Craig's (1961)meteoric water line and the Adak precipitation line are plotted on fig.9 for comparison.Adak is located in the Aleutian chain about 600 km west of Unalaska,and is the only station in the Aleutians for which stable isotopes of precipitation have been analyzed.The Adak line was derived by a linear regression analysis of 60 data points.The coefficient of determination for the line is 0.88.The data was obtained from the International Atomic Energy Agency,Vienna,Austria.Analyses of stable isotopes were performed on total precipitation,collected monthly at 4 m abovesealevel.Precipitation on Adak for which §"0 and §D data are available, cover the years 1962-1966 and 1973.Reported values from Adak for §0 and §D range from (-14.8,-111.4)to (-4,-28).This wide range partially reflects seasonal variations,but probably also the difference in isotopic composition of precipitation derived from colder Bering Sea waters vs.warmer North Pacific waters. The Adak precipitation line deviates only slightly from Craig's Meteoric Water Line.The Makushin area is affected by the same weather systems as Adak and the precipitation line for Makushin is likely to be similar to Adak.Many of locally derived meteoric waters (LDMW)at Makushin,howeyer,tend to fallslightlytotheleftoftheprecipitationlines,with $0 values 0.2 to 1.0/oo lighter than the precipitation trend.The LDMW data shows considerable scatter but tends to parallel the meteoric water lines. The isotopic compositions of most deep geothermal waters have been related to that of local meteoric waters but in general the compositions do not lie on the meteoric water line (Truesdell and Hulston,,3980).Although §Dcompositionsaresimilartometeoricwaters,%0 compositions are generally shifted toward high values.These shifts,typically on the order of3to5°Joo for high temperature systems,are caused by §"0 exchange between hot rocks and deeply circulating meteoric waters.A comparable shift in D does not occur because rock minerals ¢gntain little H,.The magnitudeofthe§0 shift depends on the original §0 values for both water and rock,the rock type,temperature,water/rock ratio,and duration of contact. Truesdell and Hulston (1980)reported that some systems in igneous rocks withanoriginal§°O +5%,maximum temperatures below 150°C and moderate water/rock ratios showed little or no isotopic shift. The thermal springs at Makushin plot closely together and fall within the range of LDMW compositions (fig.9).The single spring which falls out of this range,pt.12,is an acid spring whose isotopic composition probably reflects non-equilibrium surface evaporation such as seen at acid-springs elsewhere (raig,1963).The majority of the Makushin thermal springs show noapparent§°O shift and appear compositionally identical to the average oftheLDMWvalues.The Cl-springs appear slightly shifted in §O with 23> respect to the average value but still fall within the range of scatter of LDMW points. The lack of any §18 shift in the HCO,-SO,thermal spring waters could be attributed to one or a combination of the following possibilities:1)the water-rock contact time was too short;2)water femperatures were too low forsignificantisotopicexchangetooccur;3)the S*°o composition of the host djgrite is similar to the LDMW.Although most igneous rocks have whole-rock$°°O values of +4 to +9,compositions can be lowered through previous exchange with meteoric waters (Taylor,1974,}3773 Truesdell and Hulston,1980).Perfit and Lawrence (1979)reported 5 O whole-rock compositions regeing from -4.1 to +7.0%for the neighboring Captain's Bay Pluton.The5S0,depleted sapples were found to correlate with zones of hydrothermalalteration.No §0 analyses of the Makushin diorite have yet been made but values similar to Captain's Bay Pluton could probably be expected. Ipgcomparison to the thermal springs,the fumarole condensates show a positiveOshiftof 1.5 /oo with respect to the meteoric water line.If,as discussed above,the superheated steam from field 3 is derived directly by adiabatic expansion of steam rising from the deep reservoir,the isotopic composition of the superheated steam provides an estimate of the isotopic composition of the reservoir waters.Using fractionation data from Truesdell and others (1977)and assuming the steam was in equilibrium with and separated from liquid water at temperatures of either 190°C (minimum estimate)or 235°C (temperature of maximum enthalpy saturated steam)ygelds deep reservoir waterisotopecompositionsof§D =-80 to -87 /oo and §0 ==7.7 to78-6 /oo respectively.gine range of §{D lies within the range of LDMW;the$°0 is shifted by +3.5 -/oo with respect to the meteoric water line. The lack.of any corresponding shift in the HCO,. SO spring waters atMakushinisfurtherevidencethesespringsareisotatedfromthedeeper reservoir by a steam zone.The condensation of superheated steam would not be sufficient to produce an isotopic composition significantly different from LDMW.For example,14 gm of superheated steam at an enthalpy of 2800 J/gm is sufficient to raise the temperature of 86 gm,gf 5°C meteoric water to the boiling point.The corresponding shift in § O caused by the mixing of condensed steam having the isotopic composition of pt.10 with meteoric waterswouldbeonly0.2 °foo,well within the scatter of LDMW values. Thus the isotopic evidence is consistent with the following model for the origin of the HCO,-SO,springs.Local meteoric waters at higher elevations infiltfrate the host diorite,and circulate to shallow or intermediate depths where they encounter and are heated by superheated steam to temperatures ¢150°C.These waters then ascend to the surface under a hydrostatic pressure head and emerge as HCO,-SO thermal springs.DatafromwellW-3 indicates circulation in Glacier Yalley 'can occur to depths of 450 m. The Cl-springs Gm,Gn,Gp appear slightly shifted in 518 with respect to the average LDMW values but still fall within the range of scatter.If the6)oaaveragevalueof-11 "/oo is accepted as the $0 composition of thechargingmeteoricwatersandthe§°0 of the deep thermal waters is taken tobe§-8.0 °loo then from balance calculations the cold and hot water fractions would be 80 percent and 20 percent respectively to produce the - 39- isotopic compositions at Gm,Gn,and Gp.Isotopic mixing,however,is not consistent with the chemical compositions of the springs.The Cl and B content of these springs,if derived from a deep hot water reservoir, indicates the fraction of hot water should be more than ate as greater at GpthanatGmandGn.No such trend,however,occurs in the $-Thus theCl-springs do not appear to be water derived from the leakage.and mixing of thermal waters from a deep hot-water reservoir. THERMAL GRADIENT WELLS Three thermal gradient wells were drilled at Makushin during the summer of 1982.The purpose of the wells was to obtain information about the shallow thermal regime and to help locate an optimum site for a deep exploratory well. The wells were core-drilled,2 in.dia,to depths of approximately 460 m (1,500 £t)then cased and filled with water for subsequent temperature logging.No fluids were sampled from any of the three wells.Detailed discussions on choosing the well sites,drilling procedures followed, temperature and lithologic logs,etc.,can be found in RGI's preliminary report on the results of the 1982 Makushin Geothermal Drilling Program.The results of this drilling program are briefly discussed here because of their obvious bearing on understanding the Makushin geothermal system and the origin of the geothermal fluids.The following discussion is based primarily on personal communication with C.Isseherdt,P.Parmentier,and S.Matlick of RGI (1982)and on well-logs and temperature profiles provided to the authors by RGI.Generalized temperature profiles from temperature logs of the three wells are shown in fig.10. Well W-1 was drilled at an elevation of approximately 550 m (1,800 ft)about 2 km west of Sugarloaf Cone,and near "Fox Canyon".The bottom of the well reached 438 m (1,435 ft),113 m (370 ft)above sea level.The well penetrated 275 m (900 ft)of Makushin basaltic and andesitic lava flows before encountering a series of cinder beds,lahars,and debris flows.The latter extended down to 372 m (1,220 ft)before Makushin diorite was finally reached. An andesitic dike,thought to be related to the Makushin volcanic rocks, intersects the diorite in the well at a depth of 420 m (1,380 ft).The well was completed July 14,1980;the temperature log shown in figure 10 was obtained September 18,1982. The temperature profile is essentially isothermal down to 215 m (700 ft) reflecting the influence of cold groundwater flow along permeable bedding planes between the lava flows.Temperatures steepen rapidly in the lower part of the well with temperature gradients measuring 70°C/100 m between 275 m (900 ft)and 335 m (1,100 ft)and 36.5°C/100 m between 335 m (1,100 ft)and 438 m (1,435 ft).Bottom hole temperature measured 100°C. The volcanic section of the hole shows little or no alteration.The diorite at the bottom of the well is reported to be highly fractured and highly altered with native sulfur,pyrite,kaolinite and other clays,epidote, quartz,anhydrite and chlorite all occuring.C.Isselhardt (pers.comm.,RGI, 1982)reports evidence for two separate episodes of hydrothermal deposition within the fractures. 4@- Well W-1 has shown the Makushin geothermal prospect and Makushin diorite both extend northeastward of Upper Makushin Valley for at least 0.5 km or more. Fractured Makushin diorite appears to be the host reservoir rock at well W-l. Well W-1 also illustrates the effectiveness of volcanic flows in masking underlying geothermal systems. Well site W-2 is located in upper Makushin Valley at an elevation of about 365 m (1,200 ft)and approximately 2 km NE of fumarole field 2 and 0.5 km SW of fumarole field 1.After passing through a 10 m thick surface layer of volcanic ash the remainder of the well was drilled through Makushin diorite down to a depth of 457 m (1,500 ft).The upper two-thirds of the section is fairly fresh diorite with minor fracturing and minor amounts of chlorite, pyrite,silica,epidote,and occasional kaolinite or zeolites either disseminated or localized in small concentrated vugs or veins.Calcite becomes more prevalent below 275 m (900 ft).A zone of moderate chloritization with considerable veining and fracturing occurs at 350 -375 m (1,150 -1,230 ft).Secondary minerals of this altered zone are clays, quartz,pyrite and epidote.. The well was completed on August 8,1982;the temperature logs shown in fig. 10 were measured in September 15,1982 (upper curve)and September 18,1982 (lower curve).Temperatures in the lower part of the well exceeded the range of the measuring device used on September 15,1982.Logging of the hole was completed with a different instrument on September 18,1982.The offset between the two curves at overlapping measurement depths is thought to be due to differences in the measuring instruments rather than a temperature drop within the hole between the time of measurements.RGI suggests the lower curve may actually be 5°C hotter than depicted in fig.10.Bottom hole temperature measured 195°C, The temperature increases rapidly between 30 -365 m (100 -1,200 ft)ata rate of 44°C/100 m.The linearity of the temperature profile indicates the thermal regime above 365 m (1,200 ft)is dominated by conduction.The gradient drops rapidly but remains positive below 365 m (1,200 ft).This depth coincided with loss of circulation of drilling fluid reported by the drillers and a marked increase in fractures reported in the well-log.These coincidences indicate convection is taking place along fractures below 365 m (1,200 ft);the loss of circulation indicates the well may have penetrated into the upper part of a steam reservoir.The bottom hole temperature is consistent with the minimum estimated reservoir temperature obtained from the superheated fumarole but lower than the gas geothermometry of table 7.If the 6°/100 m positive temperature gradient continues below 457 m (1,500 ft)the temperature of maximum enthalpy saturated steam would be encountered at a depth of 1,200 m. The third well,W-3,was drilled in upper Glacier Valley at approximately 305 m (1,000 ft),on a terrace adjacent to thermal spring Gj.Fumarole fields 3,4 and 9 indicated the existence of a high-temperature reservoir at the heads of Glacier Valley.Site W-3 was chosen in part to try to delineate the lateral extent and influence of this high temperature resource and to also provide information regarding subsurface hydrology and the nature and origin of the upper Glacier Valley spring systems. -4|- After penetrating a 10 m thick surface layer of glacial till the Makushin pluton was encountered and extended to the bottom of the well,457 m (1,500 ft)below the surface.Nearly the entire section of diorite has localized zones of alteration associated with fractures and veins.One highly altered and fractured zone occurs at 60 -115 m (200 -380 ft).Another altered zone, possibly representing a recemented fault zone,occurs at 260 -265m (845 -865 ft).Alteration minerals throughout include kaolinite and clays, pyrite,calcite,quartz,chlorite,and epidote. The well-loggers reported encountering artesian flow at a depth of 60 -70m (200 -250 ft)coincident with the fracture zone described above.Wellhead flow rate was 600 Ipm with a head-pressure of 6 m. Well W-3 was completed on September 8,1982;the temperature profile in fig.10 was obtained on September 18,1982.Temperatures in the hole increased markedly (approximately 10°C)with respect to measurements made three days previously indicating the well had not yet attained equilibrium by September 18,1982. An abrupt increase in temperature occurs between 60 -75 m (200 -250 ft),the zone of artesian flow.Another but smaller increase in gradient occurs at 120 -150 m (400 -500 ft).The profile fluctuates slightly in the lower section of the well with the thermal gradient becoming negative near the bottom. Bottom hole temperatures measured 77.5°C;the maximum temperature,measured at 425 m (1,400 ft),was 80°C.Equilibrium temperatures are likely to be higher throughout much of the well. The increases and fluctuations in gradient and roll-over at the bottom all indicate a convection dominated regime at W-3.The well appears to have failed to penetrate through the zone of circulation of meteoric waters. MODEL OF GEOTHERMAL SYSTEM New geologic,geochemical,and isotopic data combined with results from thermal gradient wells have now provided sufficient detail to allow speculating on a model of the Makushin geothermal system.The summit collapse caldera indicates the existence of a shallow magma chamber beneath Makushin volcano.Age of caldera formation is unknown but is thought to be late Pleistocene or Recent.The cooling magma would provide the heat source for driving the Makushin hydrothermal system.Fumarolic activity,zones of warm ground,and HCO,-SO,thermal springs occur in an arcuate band along thesouthandeastPranksofthevolcano.The distribution is roughly concentric with the form of the volcano and summit caldera which indicates the fumarolic gases and steam are derived in large part from a core region beneath and associated with the Makushin central vent of volcanic activity. The extent of surface thermal activity provides a minimum estimate of the size of the subsurface system (fig.2).Fumarolic activity implies the existence of a steam cap on the hydrothermal system,the bottom of which must extend at least down to 365 m (1200 ft),the lowest fumarole in field 3 and field 1. Discharge of HCO 50,thermal waters at lower elevations peripheral to thefumarolicactivityindicatesthesubsurfacevaporzoneextendslaterally beyond and is lower in elevation than the lowest fumaroles.The loss of - Y44- circulation of drilling fluid and the evidence for convection in the botton of well W-2 suggests a vapor.zone may exist at depths of 100 meters below sea level in the upper part of Makushin Valley. The host reservoir rock for the geothermal system appears to be the fractured Makushin diorite pluton.Much of the thermal activity at the surface coincides with the exposure of the diorite at the heads of Makushin and Glacier Valleys.Makushin volcanic flows and units in the Unalaska Formation serve as effective cap rocks elsewhere.Volcanic flows may also be directing fluid flow laterally outward from the core region to the periphery of the volcano where the diorite is exposed. Based on thermodynamic considerations of the superheated fumarole and the temperature log from well W-2 deep reservoir temperatures must exceed 190°C, Gas geothermometry suggests reservoir temperatures of 235-300°C..The existence of a vapor-dominated system at 235°C overlying a hot-water reservoir is suggested but not proven by the gas geothermometry,characteristics of well W-2 and the existence of the superheated fumarole. Gas composition in the deep reservoir,is ost apt to resemble that of thesuperheatedfumarole(Table 3).The He/He compositions of fumarole and hot spring gases indicate a magmatic influence on the geothermal system. Variations in He/He compositions may reflect varying degrees ofhot-water leaching of radiogenic "He from reservoir wall-rock.Isotopic composition of the CO,indicates it is primarily derived from the cooling intrusive.H,S is also probably largely derived from the magma.Other gases present primarily originate from water-gas and water-rock reactions or from gases dissolved in the changing meteoric waters.Isotopic composition ofwatersinthedeepreservoirisestimatedtobe$0 -8 °/oo and §D=-80to-86 °/oo.The range of D is similar to LDMW samples from Glacier and Makushin.Valleys,but much heavier than snow melt from the summit of Makushin. Meteoric waters charging the deep system therefore appgar to originate atlowerelevationsontheflanksofthevolcano.The $°°O is shifted + 3.5 percent with respect to LDMW.Water chemistry of any underlying hot-water reservoir is presently unknown.The Mg-rich Cl-springs in Glacier Valley do not appear to be directly related to the deep reservoir. Thermal springs in upper Makushin and Glacier Valleys are rich in HCO,, SO,,and Ca and originate from the circulation of meteoric waters along fractures in the Makushin pluton.The waters are heated by ascending steam and hot gases and by conduction from wall-rock.Low Cl concentrations indicates isolation from any deep hot-water system.If the SiO,in the waters is assumed to be in equilibrium with quartz cr chalcedony,temperatures at the base of circulation would range from 100-150°C.Isotopic evidence indicates the charging waters in both areas are of local origin.Results from Well W-3 indicate the depth of circulation of thermal waters in upper Glacier Valley is 400-500 m.Lower concentrations of dissolvéd solids in thermal waters suggests shallower circulation of meteoric waters in upper Makushin Valley.Fracturing and alteration of the host Makushin pluton are more intense and more pervasive in Upper Glacier Valley than in Makushin Valley which probably accounts for the greater number of thermal springs found in Glacier Valley.The high temperatures encountered in well W-2 suggest the heat sources for springs in Makushin Valley lie beneath the springs themselves,Well W-3 failed to penetrate beyond the zone of meteoric water circulation and it is not clear whether springs in Upper Glacier Valley are _43- heated directly from below or by lateral flow of waters and through the zones of fumarolic activity above the spring sites. Three possible origins are suggested for the Mg rich Cl-springs in Glacier Valley:1)Mixing of Cl-rich deep thermal waters with cold near-surface waters;2)circulation of meteoric waters in isolated systems associated with local faults in Unalaska Formation rocks;3)circulation of HCO,.-SOwatersthroughUnalaskaFormationrocks.The high concentrations of HCO and SO,in these spring waters suggest a gas influence on the waters. Isotopic evidence suggests the Cl-waters are not related to deep thermal waters.Isotopic and chemical evidence favors either the second or third possibility or both. 3 Hydrothermal activity appears to have been more widespread in the recent past. Several mounds and areas of hydrothermally altered glacial till and fluvial sediments can be found in Glacier Valley. Most of the surface thermal activity appears focused at the heads of Glacier and Makushin Valley.This zone appears to be at the intersection of several features:1)the lineament trending down Glacier Valley and Driftwood Valley;2)which is more or less tangent to the arcuate zone of fumarolic and thermal spring activity;3)the alignment of satellitic volcano vents;4) exposure of glacier-eroded diorite. These observations and speculations suggest a model in which meteoric waters on the flanks of Makushin Volcano infiltrate into a deep hot-water reservoir at 300°C where the waters are heated by a cooling magma related to the recent caldera forming eruption.Geothermal waters boil at a temperature of somewhere between 190-235°C to form a vapor-dominated zone,steam and gases from which feed the numerous fumaroles on the south and east flanks of the volcano.Part of the steam heats meteoric waters which circulate from shallow to moderate depths along fractures in the host diorite before emerging as HCO.,-SO,thermal springs.The distribution of fumaroles and springs suggests upward and lateral flow of steam and gases along fractures in the diorite from a core region beneath the volcano.Flow of hot fluids may be partially directed by overlying Makushin volcanic flows.Steam may also be ascending vertically along the lineament in Upper Glacier and Makushin Valleys. Although the above model assumes a "wet"saturated system,the possibility the deep system may be "dry"cannot be dismissed,particularly if the intrusive(s) driving the system is of a very young age. POTENTIAL DRILLING SITES Strong evidence exists for a central geothermal system beneath Makushin volcano giving rise to the fumarolic activity and thermal springs on the south and east flanks of the mountain.The evidence also supports but does not confirm the interpretation that the steam cap extends down into a vapor-dominated reservoir underlain by a hot-water reservoir. -44- How far the central geothermal system extends beyond the surface manifestations of heat and whether a geothermal system exists beneath the Glacier Valley lineament are not yet known.Prudence therefore dictates siting the deep exploratory test well as close as reasonably possible to the core region of the volcano.Based on geologic grounds the most logical choices would be at or near fumarole field 2 or 3 where the existence of a high-temperature resource is evident from the intensity of thermal activity. The lack of a road,however,makes use of a helicopter and and helicopter-transportable drill-rig mandatory for the exploration well. Logistically the steepness of terrain,high elevation,and difficult accessability make these sites impractical for helicopter landings and for the only helicopter-portable drill-rig available in Alaska capable of well depths of >6,000 ft. RGI has recommended siting the deep exploratory well near thermal gradient well W-2.The site is located near regions of fumarolic and thermal spring activity and lies along the Glacier Valley lineament.Temperatures and evidence for convection at the bottom of W-2 suggest a high-temperature steam resource capped by unfractured diorite.The site has proven to be logistically accessible and provides a broad flat area for construction of both a camp and drilling platform.RGI has proposed to try to direct the drilling angle towards the volcano to enhance the potential of intersecting a developable high-temperature reservoir.Upon considering the geologic field evidence,the logistical accessibility,the anticipated size of the drill-rig required,and the evidence from well W-2,the authors are compelled to concur with RGI's choice for the site of the first deep exploratory well at Makushin. _f5- ACKNOWLEDGEMENTS Funding for the Makushin geothermal fluids investigations comes from the State of Alaska,DGGS volcanic-geothermal atlas program and from the Alaska Power Authority under Makushin RSA number . The authors wish to acknowledge helpful discussions with representatives of Republic Geothermal,Inc.,C.Isselhardt and P.Parmentier,and with colleagues within DGGS,C.Nichols,J.Reeder,and M.Henning.Dr.J.Welham of the Scripps Institute of Oceanography and Dr.A.Truesdell,K.Janik,M. Stallard,and R.Caruthers of the U.S.Geological Survey,Menlo Park, California provided lab facilities and assisted in analyses of gas and iso- topic compositions contained in this report. The valuable field assistance of G.LaRoche and C.Nye are also gratefully acknowledged.Figures appearing in the text were prepared by S.Liss and J.Filot. Ab- REFERENCES Barnes,Ivan,1964,Field measurement of alkalinity and pH,U.S.Geological Survey Water-Supply Paper 1535-H,17 p. 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Reeder,J.W.,Nichols,C.,Motyka,R.,and Henning,M.,1982,Makushin Volcano geothermal resources,informal report,Alaska Division of Geological and Geophysical Survyes,submitted to the Alaska Power Authority. Richet,P.,Bottinga,Y.and Gavoy,M.,1977,A review of hydrogen,carbon, nitrogen,oxygen,sulfur,and chlorine stable isotope fractionation among gaseous molecules,Annual Reviews of Earth-Planetary Science v.5,pp. 65-110. Rolson,J.H.,den Hartog,J.,Butler,J.P.,1976,The deuterium isotope separation factor between hydrogen -liquid water,Journal of Physical Chemistry,v.80,pp.1064-1067. Sackett,W.M.,and Chung,H.M.,1979,Experimental confirmation of the lack of carbon isotope exchange between methane and carbon oxides at high temperatures,Geochimica et Cosmochimica Acta,v.43,p.273-276. SEAN (Scientific Event Alert Network Bulletin),1980,National Technical Information Service,U.S.Department of Commerce publication no.PR 81-9157. 49- Seward,T.M.,1974,Equilibrium and cxidation potential in geothermal waters at Broadlands,New Zealand,American Journal of Science,v.274, p.190-192. Taylor,H.P.,Jr.,1974,The application of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition, Economic Geology,69,p.843-883. Taylor,H.P.,Jr.,1977,water-rock interactions and the origin of H,O in granitic batholiths,Journal of Geological Society of London,v.133,p. 509-558. Torgersen,T.,Lupton,J.E.,Sheppard,D.S.,Giggenbach,W.F.,1982,Helium isotope variations in the thermal areas of New Zealand,Journal of Volcanology and Geothermal Research,v.12,p.283-98. Torgersen,T.,Jenkins,W.J.,1982,Helium isotopes in geothermal systems: Iceland,The Geysers,Raft,River,and Steamboat Spring,Geochimica et Cosmochima,v.46,p.739-48. Truesdell,A.H.,1976,Geochemical techniques in exploration,Proceedings of Second United Nations Symposium on the Development and Use of Geothermal Resources,San Francisco 1975,1.p.liii-Ixxix. Truesdell,A.H.,Nathenson,Manuel,and Rye,R.O.,1977,The effects of subsurface boiling and dilution on the isotopic compositions of Yellowstone thermal waters,Journal of Geophysical Research,v.82,p. 3694-3704. Truesdell,A.H.,and Hulston,J.R.,1980,Isotopic evidence on environments of geothermal systems,in Handbook of Environmental Isotope Geochemistry: Elsevier,p.179-219. Truesdell,A.H.,and Thompson,J.M.,1982,The geochemistry of Shoshone, Geyser Basin,Yellowstone National Park,in Thirty-third Annual Field Conference -1982,Wyoming Geological Association Guidebook,p 153-159. Welhan,J.A.,1981,Carbon and Hydrogen Gases in Hydrothermal Systems:the Search for a Mantle Source,Ph.D.Thesis,University of California,San Diego,182 p. Wescott,E.M.,Turner,D.L.,Motyka,R.J.,Witte,W.,and Petzinger,B.,1982, Helium and mercury surveys of parts of Unalaska Island,report submitted to Alaska Division of Geological and Geophysical Surveys. White,D.E.,Muffler,L.J.P.,and Truesdell,A.H.,1971,Vapor-dominated hydrothermal systems compared to hot-water systems,Economic Geology,v. 66,p.75. -§0- Table 1.Description of fumarole fields and areas of geothermally heated ground at and near Makushin Volcano l.Fumarole field:Located in Makushin Valley about 4 km SW of Sugarloaf Cone (fig.2).The site occurs on the steep northern valley wall at 360melevationandconsistsofa2,500 m area of mild boiling-point fumarolic activity,mudpots,and heated ground.Hot springs occur immediately below the fumaroles.The fumaroles emanate from colluvium overlaying Recent Makushin volcanic flows. 2.Fumarole field:Located on a steep southeast facing slope at the head of Makushin Valley between elevations of.640 and 820 m.Thermal activity consists of numeyous ,boiling point,mildly pressurized fumaroles covering anareaat0.25 km'.The vents tend to occur in linear clusters oriented 310°suggesting fractures control the fumarolic conduit system.The fumaroles emanate from the Makushin diorite which has been fractured and intensely hydrothermally altered in this vicinity.The west end of the fumarole field is capped by Makushin volcanic flows. 3.Fumarole field:Located at the head of Glacier Valley on a steep bluff that lies between two deep canyons.Several zones of fymarolic activity and hydrothermally altered ground cover an area of "0.5 km'between elevations of 370 and 600 m.The fumaroles emanate from the Makushin pluton.A highly pressurized superheated fumarole (152°C)occurs beneath a steep cliff of capping Makushin volcanic flows at an elevation of 600 m.A neighboring fumarole with much lower pressure measures 105°C.Fumaroles elsewhere on the bluff are mildly pressurized and at the boiling point. 4, Fumarole field:Located at 630 m near the margin of a glacier that descends into a western tributary valley of Glacier Valley.Fumarolic activity and mudpots cover several hundred m™and emanate from a Recent lateral moraine.Bedrock above the moraine is Makushin diorite.Two of the fumaroles are highly pressurized and spew jets of hot water and steam as a result of stream water infiltrating into the vents.These two vents could not be reached for temperature measurement;other vents in the vicinity were at boiling point. 5.Fumarole field:Located on the south flank of Makushin at 870 m elevation.The fumaroles occur in a 100 m diameter hole melted through a thin cover of glacier ice.Vent temperatures were slightly superheated (99-100°C).One fumarole is highly pressurized and periodically ejects jets of hot water and steam.The geyser-like activity is probably caused by meltwaters flowing into the superheated vent.Rocks in the glacier hole are bedded volcanoclastics,possibly part of a debris flow. 6.Fumarole field:The largest and most prominent area of thermal activity, located at the active volcanic crater near the center of the otherwise ice-filled summit caldera of Makushin Volcano.Maddern (1919)reported sulfur deposits in and around the crater and observed several loud,high-pressure fumaroles,one of which he measured at 150°C.Several high pressure fumaroles on the flanks of the active crater and a conspicuous vapor plume emanating from the active crater were observed during a reconnaissance to the summit in -S5l- July,1982 by one of the authors (Motyka).Sulfur deposits ringed several of the vents and sulfur fallout from the crater plume coated the snow surface downwind of the water.Ice hazards and noxious gases prevented temperature measurements of.the high-pressure fumaroles in 1982 but the vents are thought to be superheated.Temperatures of small steam vents in an adjacent ice-free ridge were all at the boiling point. 7.Fumarole field:located on the north flank of Makushin at an elevation of 820 and 860 m.The site is reported to consist of mild boiling pointfumarolicactivitycovering11,000 m'.(Reeder,1982).Rocks in the vicinity are Makushin volcanics. 8.Warm ground:Located on a ridge about 1/2 km SW of Sugarloaf cone at gnelevationof525m(Wescott and others,1982).The site consists of 100 m of anomously warm ground.Temperatures measured as high as 85°C at 0.75 m depth.The knoll of warm ground lies on a ridge composed of late Quaternary basaltic flows. 9.Fumarole field:Located at an elevation of 475 m in a western tributary valley of Glacier Valley,south of fumarole field 4.The site,consists ofmudpotsandmildfumarolicactivitycoveringanareaof100m'.The fumaroles emanate from a Recent moraine.Bedrock exposed above the moraine is Makushin diorite. 10.Warm ground:An area of hydrothermally altered ground with a sulfurous smell was reported by M.Henning (DGGS,pers.comm.)and P.Parmentier (RGI, pers.comm.)to occur at the head of Makushin Valley at an elevation of 7800 m (2,600').Bedrock in the vicinity is believed to be Makushin diorite. ll.Steaming ground:an area of hydrothermally altered ground was reported to be "steaming"by P.Parameter and C.Isselhardt (RGI,pers.comm.,1982)on the NE facing slope of Fox Canyon. 12.Snow free ground:An anomalously snow-free area of ground was reported by P.Paramenter and C.Isselhardt (RGI,pers.comm.,1982)to exist about 2 km north of Sugarloaf Cone.Ground temperatures several cm below the surface measured 20°C. -5 27 -=S-cube subecheated fog 'oe Vapet east fers slacter Valley Vater east Cork Giteter Vabley Contluence of two upper dratnages of stacter Vallev "pper Glacter Valley Upper Glacter Valtey Upper Glacter Valley Upner Glacier Valley Table 2,Nescription of therma!spring sites,Makushin peothermal area. BHEDROCK Yreactured Matushin diorite Fractured Mahushin drorlte Makushin Makushin dlorite Makushin diorite Makushin diorite Nakushin diorite Makushin diortte TEMP (°C) 70-96 50-55 76-99 40-68 17-78 50-64 40-62 FLOW (lpm) (20) (40) (200) (20-25) (50-60) (35) (50-60) CHARACTERISTICS Acid springs issuing near superheated tumarote, Springs issue from bluff wall. Waters fesue from recent glacial e111 on steep bluffside, Acid springs and NCO,-S0 waters with low Clemergeatbaseoffuparofetleld3.Channels near vents lined with 1-2 cm catcite.,Serong 1,5 odor, Waters emerge from west side of valley -base of wall through calcite cemented alluvium and colluvium -thin calcite apron covering ground below vents, HO,-SO,waters with low C]issue fromcolluviumatbaseofE.valley wall mainly as seeps,One spring emanates from a small calcite sinter cone.Calcite coated channels and ground indicate previous Jarpe flow rate. Waters issue from recent glacial moraine on east side of valley. Springs emerge from boulders alung stream bank on west side of valley.Abundant calcite tn channel,Several warm swampy punds. -hS ont unk Goa Unpee Clacter Valley Upver Glactor Valley Vnner Wore Verk ot acset ee West Bork C'icter River Mear mouth of lower weet fork to Glacier Valley Glacter Valley Intersectton of Pahushin Valley & Glacter Valley Upper Makushin Valley Vooer "akushin Valley 'ahushin 63 (20) cioriee Soakushin 40-55 (40-60) Vrorite Makushin 99-100 (10) diorite Makushin $0-64 310-340 diorite "nalaska 38-44 (20) Unalaska 27-33 (10) Formation "nalaska 40 (10) Sormat ion Makushin 99 (20) dforite with pyrice & chalcopyrite, Makushia 80-88 (49) Jforile 3? Springs issue from recent medial moraine -seme calcite sinter, Waters flow from 3 vents 5-6 m apart on went side of valley.Calecitle-travertine deposits 1-3 cm thick near oriifees of alt ventn. Actd springs,mud pots and hydrothermally altered ground occur along a fissure Crending 1O4°-110°,Springs are located near margin of glacier. Numerous springs emerge from cliffs above North bank of stream just beyond #bedrock constriction of stream channel.43°C warm marsh 59 w up valley. Ul waters emerge in warm pond along stream channels. Cl springs emanate from marshy area with lush vegetation, C)springs issue into shallow pools fa marshy area, Acid waters jasue from Fissures in bedrock near lumarole field 2 -ather springs in area YU"U and others unreachable, RCO SO,water,slightly acidic,emerge insma?bowl in glacier drift with reddish oxide staining adjacent rocks. -GoG--Mec Nroee Makushia Valley weot ts bhutary Med Vpper Makushin Valteyv west Oribucary *values in parentheses ore "Sokushia clortte basate and SMavous tba voloantes Makushin veleantcs 40-54 35-67 3a (20) (50-60) Springs emanate from base of cliff into pond on stream terrace, HCO,-S0O,waters issue from col luvium accumulated on a bench 75 m above stream, Springs are adjacent to fumarole tield |. -7G-Table 3.Chemical composition of fumarole and thermal spring gases from .Makushin Volcano thermal fields,preliminary results,mole percent. 12 2°2°34 3°3f 58 6 =gt co 91.68 87.90 86.39 87.11 94.81 81.20 92.3 87.51 93.9H,8 2.63 2.65 5.89 1.55 10.81 0.8 5.53 3.0 H 0.24 0.54 0.74 1.80 1.12 1.23 0.58 0.28 0.72ch,-0.03 0.002 0.021 0.02 0.006 0.07 nd 0.07 nd N,5.36 8.81 6.87 9.41 4.04 4.43 3.6 5.64 6.2 Ag 0.07 0.09 0.06 0.11 0.04 0,oo oo DOA yg 0.42 0.1 0.06 0.6 Ha (ppm)8.0 5.6 8.1 4.5 3.0 4.25 nd 17.4 nd T (°C)----98 98 78 98 152 98 96 97 Date Sampled 8/13/80 8/13/80 7/14/81 7/5/81 7/5/81 7/8/82 7/13/82 7/18/82 7/14/82 (a)Steam vent,field #1 (b)Steam vent near center of field #2 (c)Steam vent near center of field #2 (d)Acid spring at base of field #3 (e)Steam vent below superheated fumarole in field #3 (f)Superheated fumarole near top of field #3 , (g)High-pressure fumarole/geyser,field #5 (h)Steam vent,near active water,Makushin Summit (1)Mudpot,fumarole field #9 nd -Not determined. bd -Below detection. -LG-Table 4.Helium Isotope Data,Makushin Volcano Fumarole Fields a \ Location Summit,#6 Makushin Valley,#1 Makushin Valley,#2 Makushin Valley,#2,Spring M-b Glacier Valley,#3,GV-1l Glacier Valley,#3 Glacier Valley,#4 West Flank,#5 Glacier Valley,Spring G-p 4)R.Poreda,Scripps Isotope Laboratory,Analyst 3byR=He/"He;Ra =air helium isotope ratio NA =not yet available R/Ra> -39--Table 5. Location Summit #6 bMakushinValley,#2GlacierValley,#3,cv-1?Glacier Valley,#3 bGlacierValley,#3,Spring G-d ab2 Carbon Isotope Data,Makushin Volcano Fumaroles 13¢_co,(PDB) wa -12.22 -10.24 -12.96 -11.75 J.Welhan,Scripps Isotope Lab.,analyst )Global Geochem,Canoga Park,CA,analystsA)Not yet available)Sample volume below detection limit of instrument 13 C-CH,(PDB) -30.6 (-24 to -36) d d -bS-Table 6.Hydrogen Isotope Data,Makushin Volcano Fumaroles Location Summit,#6?aGlacierValley,#3,GV-l bGlacierValley,#3,Spring G-d i)M.Stallard,USGS Isotope Lab,Menlo Park,CA analyst©Global Geochem.,Canoga Park,CA analysts)Sample volume too small for analyses _§D-H, -719 582 601 §D-CH, -132.6 Cc ¢ Table 7.Geothermometer of D'Amore and Panichi (1980)applied to Makushin fumaroles and thermal spring gases (all temperatures in +C).. Makushin Valley Fumarole in #1 230 Fumaroles in #2 (b)238 (c)281 Glacier Valley Fumarole field #2 Acid spring 288 Superheated fumarole ,297 Summit Fumarole near active crater (3)239 -(p0- -|9-Table 8.Water chemistry,Makushin Valley thermal springs. sio Fe Ca Mg Na K Li Sr 2 SO Cl F B TDS (calc) pH,field T (°C) Date sampled 84 7/17/82 2.M b 140 0.1 69 12 28 5.6 0.01 0.3 19] 155 5 0.12 0.5 510 5.5 87 8/13/80 3.M-c 5.5 .mOdNooLoonMNAnAoowsnr7/18/82 Units are mg/l unless otherwise noted. 5.M-d 88 0.0 23 8.0 14 3.4 0.01 0.1 116 21 5 0.1) 0.5 217 5.32 67 8/13/80 Table 9.Water chemistry,Makushin and Driftwood Valley 'cold streams and springs. 6.Cold spring at W-2 7.Cold stream,Driftwood Valley S10,13 4.5 Fe 0.1 0.1 Ca 1.8 2.6 Mg 0.6 0.5 Na 2.6 2.0 K 0.2 0.1 Li 0.01 0.01 Sr 0.1 0.1 HCO,ll nd SO,2.8 3.1 Cl 3.7 2.6 F 0.1 0.1 B 1.0 0.5 TDS (calc)30 - pH field 6.6 nd T (°C)6.5 3.8 Date sampled 7/19/82 7/1/81 (,Q- -¢4)-Table 10.Water chemistry,Glacier Valley thermal springs.Units are mg/l unless otherwise noted. 8.G-dl 9.G-d2 10.G-d3 11.G-e 12.G-f 13.G-h 14.G-j{15.G-l 16.G-m 17.G-n 18.G-p S10,94 125 120 138 142 145 120 135 113 119 104 Fe 0.1 0.0 nd 0.0 0.2 0.4 0.7 0.5 1.7 1.9 2.1 Ca 12 32 25 258 208 243 275 262 203 179 159 Mg 4.0 11 8.0 9.6 7.8 1]11 10 15 23 38 Na 52 87 62 61 81 64 53 63 176 176 299 K 4.8 5.7 5.2 3.3 4.8 3.8 3.4 -4A5 19 19 31 Li 0.01 0.01 0.01 0.04 0.03 0.03 0.03 0.03 0.48 0.40 0.86 Sr 0.1 0.3 0.2 0.1 0.1 1.2 1.4 1.2 1.1 1.0 1.4 RCO,18.5 288 3 nd 256 358 332 325 463 563 590 SO,129 95 218 491 476 472 581 542 363 321 178 Cl 10 5 6.1 2.3 7.5 5.8 6.6 6.6 164 142 382 F 0.14 0.28 0.1 0.26 0.24 0.1 0.1 0.1 0.1 0.1 0.1 B 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 4.2 4 9.9 Br nd nd nd nd nd nd nd nd 0.1 0.1 Tr TDS (calc)305 503 446 -1054 1122 1214 1185 1286 1258 1495 pH,field 6.4 6.5 4.3 nd 6.4 6.0 6.1 6.0 5.9 5.8 6.3 T (°C)97 82 78 68 79 60.5 41.5 62.5 39 27 40 Date sampled 8/11/80 8/11/80 7/15/81 7/5/81 7/5/81 7/11/82 7/10/82 7/13/82 7/20/82 7/20/82 7/20/82 "4-Table 11.Water chemistry,Glacier Valley cold streams and springs.Units are mg/l unless otherwise noted. SidFe 2 Ca Mg Na K Li Sr SO Cl F B TDS (calc.) pH,field T (°C) Date sampled 19.Cold stream at G-d 20.Cold spring at G-j 21.Cold stream at G-l iedNsoOoOMUMUnOOOfKDOOeeee¢e.neO3a7/15/82eOOOnOORe-.Je-°mOWee-NhDBDOOWTUnsNDODOLHPKYFOOMee«.eUm66nN7/13/82 -S9 Table 12.Silica and cation geothermometers applied to Makushin thermal springs.Temperatures in °C. Surface Quartz Na-K-Ca-Mg, Spring temperature conductive Chalcedony Amorphous Na-K Na-K-Ca,4/3 Na-K-Ca,1/3 _corrected Mc 34 140 114 19 244 50 162 --- Gf 79 158 134 36 176 29 125 --- Gh 61 159 135 37 176 20 121 --- Gm 39 144 119 24 225 76 166 --- Cp 40 139 112 18 221 104 175 70 Table 13.Stable isotope data,Makushin thermal springs,steam condensates, and locally derived meteoric waters.All values reported relative to SMOW. bb- Location Type $18 §D Year of analysis Makushin Valley M-a SO,-HCO,hot spring -11.05 -77 1982 M-b so "HCO,hot spring -11.9 -78 1980 M-b cotd stream 13.0 -89 1980 M-c SO,-HCO,hot spring -12.4 81 1981 M-c so "HCO,hot spring -11.7 -84 1982 M-c cota stream 11.9 82 1981 M-d so "HCO,hot spring 12.1 -81 1980 M-d cota stream -11.3 -83 1980 M-Camp Cold spring -9.65 -67 1982 Glacier Valley Fumarole 3 Steam condensate -10.4 85 1982 Fumarole 3 Cold stream -13.5 -88.5 1982 G-dl Acid hot spring -8.9 -70 1980 G-d2 SO,-HCO,hot spring -11.6 -80 1980 G-d3 sO "HCO,hot spring -11.9 -83 1981 G-d Cold spzing "11.1 -77 1980 G-d Snow run-off -11.2 -76 1980 G-d Cold stream 12.0 -86.5 1980 G-d Cold stream -14.2 -93 1981 G-e SO,-HCO,hot spring -12.2 -80 1981 G-f SO,-HCO,hot spring -12.5 -83 1981 G-h SO,-HCO),hot spring -11.7 -82 1982 G-j SO HCO,hot spring 11.0 -79 1982 G-k cota spring -10.1 -76.5 1982 G-1 SO "HCO,hot spring -11.9 -83 1982 G-1 cotd stYean -12.6 -88 1982 G-n Cl -hot spring -11.1 -80 1982 G-n Cl -hot spring -11.05 -82 1982 G-p Cl -hot spring -10.9 -78 1982 Summit Fumarole 6 Steam condensate -13.0 -107 1982 Fumarole 6 Snow melt -15.9 -121 1982 10. FIGURE CAPTIONS Site map and generalized geology of northern Unalaska Island. Location map of thermal springs,fumaroles,and hot ground in the Makushin geothermal area.Geology is taken from Drewes and others,19613 Henning and Reeder,1982;and P.Parmentier,RGI,personal communication, 1982, Enthalpy vs.pressure diagram taken from Muffler and others (1982) showing the relations between saturated steam and the isothermal decon- pression paths of superheated steam.The dashed line shows the iso- enthalpic decompression path between saturated steam and the superheated fumarole at field 3. §13¢compositions of CO,at Makushin compared to other geothermal areas.Diagram taken from Truesdell and Hulston (1980). §D compositions of H,and CH,at Makushin compared to other geothermal areas and volcanic vents.Data for Japanese areas,Iceland, and Yellowstone taken from Kiyosu (1982);data for Salton Trough and EPR 21°N is from Welhan (1981). Carbon isotope compositions of co-existing CH,and CO,from volcanic, geothermal,and sedimentary sources.Diagram taken from Truesdell and Hulston (1980).Fractionation temperature data from Bottinga (1969). Trilateral diagram showing percentage cation compositions of thermal springs and locally derived meteoric waters at Makushin.Numbers are keyed to Tables 8,9,10,and 11. Trilateral diagram showing percentage anion compositions of thermal springs and locally derived meteoric waters at Makushin.Numbers are keyed to Tables 8,9,10,and ll. Diagram of stable isotope composition of Makushin waters.Values are relative to SMOW.Numbers are keyed to Table 13.Craig's (1961) meteoric water line and the Adak precipitation line,discussed in text, are included for comparison. Temperature profiles for thermal gradient wells in the Makushin geothermal resource area.Temperature logs are from September 18,1982 for W-l;September 15,1982,upper curve,and September 18,1982,lower curve for W-2;and September 18,1982 for W-3.Data provided by RGI. (p7- 166 30°167°00° 1 ' Glacier &7 9 Surficial deposits '$s ®sal Eider Point basalt &>oo Satellite vents " 'f EE]Ja 0gs_Makushin volcanics "13.58¢3 e"8a<7GranodioriteUnalaska4plutonsformationg¢=oO |:MaAa Pakeete '-Fault 2 ED Caldera kd Stratovolcano 6 [=€<=4/£5 mi.g Kjsa}5 km.46 GENERALIZED GEOLOGY Adopted from Drews &Others (1961) Henning &Reeder (1982) Fe aan nee? Site area 167 00 166 30 " /Pakyshin 0 pol Con Pm,rece)_hp - VA 1/vit a :;*ae ;CO,st ai |lias filesN-2 a ' J pong yom : 6'tas yy . a Lt Ma / .i 794 me Mb JS 8 eprh Om Z "ee Superheated fumarotey aN c - bf Springs ©Fumarotes O Heated ground &Wells ()Makushin pluton omer =Faults o+-°o-rath,.eStinalastas\taged/Km,Area oe Mi.ot rR Wi NORTH UNALASKA ISLAND LOGPRESSURE,BARS2.07 =Maximum enthapy point 260 for satuated steam 16- \D>240 bh 7 220 1.2 4 200 : 4 180 t t 1 i] 0.8 7 160 1 t -1 t J i] 140 ' 0.4-! t 120 ' a 4 4 t i] i] 4 07 i 1512 -0.4 T T mf 2600 2700 2800 2900 3000 ENTHALPY,J/g T0- MAKUSHIN ASA A CERRO PRIETO a secre <e*e efee NEOTERCCORES-e °°:€0C04 YELLOWSTONE 2 3088 ose oes .aa ae TERRACES LARDERELLO a4 PUNA znet|*KILAUEA SULPHUR BANK CORES SURFACE 3 .eSTEAMBOATee PRIN 3SPRINGSte ©SURFACE4HCO?"Q>oRULHOLE 0°4 SAMPLES LASSEN . a @Cec03o44OHCOs. 4 acOg"THE GEYSERS'2 0OC@ 0 a 2 as DIAMONDS:itesEsitet oe] =7 fy MMESTONES 3],"12.10 8 6 4 2 [°2 5 C'3(°/o9) 4 4 8 10 Makushin Salton Trough EPR 21°N Surtsey Zao Azuma Nasu Kusatsu shirane Matsukawa Iceland Yellowstone Summit Gd GV-1 Summit |\/| e ee ro. e os obe noce-S-e r @-ernz3-e e - Te-e-0 ©6 e © 00-0 °2 ose e-8 32089 o03 oe @ oe 2 CO-ooe l i !!{i -600 -400 -200 D(%o0) -"]2- >OF Sample Code Makushin Valley: l.Hot 2.Hot 3.Hot 4.Hot 5.Hot 6 .Cold spring,camp Driftwood Valley: 7.Cold Stream Glacier Valley: 8.Hot 9.Hot 10.Hot ll.Hot 12.Hot 13.Hot 14.Hot 15.Hot 16.Hot 17.Hot 18.Hot 19.Cold Stream at G-d 20.Cold Spring at G-j21.Cold Stream at G-1 Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring Spring 330-32 KEUFFEL &ESSER CO,c % Triangular Co-ordinate. wa. M-a M-b M-c,1981 M-c,1982 M- d G-dl G-d2 G-d3 G-e G-f G-h G-4 G-1 G-n G-n G-p SeanaaAaaeTAVAVAVASATASAYI am ;350+ANASmeus OO ” SL-359-32 KEUFFEL &ESSER CO. cS Sample Code Makushin Valley: 1.Hot Spring M-a 2.Hot Spring M-b 3.Hot Spring M-c,1981 4.Hot Spring M-c,1982 5.Hot Spring M-d 6.Cold spring,camp Driftwood Valley: 7.Cold Stream Glacier Valley: 8.Rot Spring G dl '9.Hot Spring G-d2 10.Hot Spring G-d3 ll.Hot Spring G-e 12.Hot Spring G-f 13.Hot Spring G-h 14,Hot Spring G-j 15.Hot Spring G-1l 16.Hot Spring G-m 17.Hot Spring G-n 18.Hot Spring G-p 19.Cold Stream at G-d 20.Cold Spring at G-j 21.Cold Stream at G-1l \. gLe e A aa Nad SOA, ehTOON AL-§D(SMow)Ia[o)\t-100 O18 'Locally Derived Meteoric Water 4 'Glacier Valley Hot Springs 'Makushin Valley Hot Springs _%_Fumaroles i]L)a) 5'8o(smow)+_-fayee - LbL-DepthMeters90 Temperature C' 190 100 +150 +200 --250 --300 7350 +-400 +450 VII.Conclusions including general drilling target recommendations In general the immediate Makushin Volcano region as outlined in Figure 14 is considered to be a "known geothermal resource area"as defined by Godwin et al,1971.This classification consideration for the immediate Makushin Volcano region has been based on geological,geochemical,and geophysical consideration; on the extent and nature of the surface hydrothermal manifestations;and on the wftemperature-gradient holes and corresponding data (Republic Geotherm,Inc.;and \e atheAlaskaPowerAuthority).Large vapor-dominated hydrothermal systems are Aesuspectedtoexistinthisregion.In addition,some small vapor-dominated rh ne?OhydrothermalsystemsareconsideredpossibleintheSugarloadCone,upper wr. Nateekin Valley,and upper Glacial Valley regions as indicated in Figure 14 as "areas valuable prospectively."Deep exploration drilling is not recommended in this region unless economic considerations completely rule out the possibility of deep exploration in the "known geothermal resource area".The rest of the region is considered to be an "area having some value prospectively."This area probably does not contain any vapor-dominated hydrothermal systems,or at least the possibility for such systems is low. Most of the unaltered volcanic rocks (i.e.,geologically recent volcanics) of the northern part of Unalaska Island would be expected to have fairly high permeabilities for fluid transport.Any heat originally contained in such rocks would have been removed fairly quickly by fluids with respect to geologic time, especially considering the wet environment of Unalaska Island.Thus,the driving heat sources for fumarole fields no.5,no.6,no.7,and possibly no.8 (all of which occur in unaltered volcanics)are probably shallow magma bodies that have been en-placed within recent times.In fact,explosive activity within historic times is highly suspected for the fumarole field no.7 region (Personal Comm.,Henry Swanson,Unalaska)and is also suspected at a less intense level for the fumarole field no.6 region.A aasonpo Large vapor-dominated hydrothermal systems probably exist in the metavolcanics and plutonic rocks within a northeast oriented zone on the southeast flank of Makushin Volcano (Figure 14),where the southeast boundary of this zone is.roughly marked by fumarole fields no.1,now 2,no.3,and no.4. The Targe N55°W,N35°E,and N85°E apparent normal faults which trend into the -78 - Makushin volcanic pile are probably the surface manifestations of dikes that did not reach the surface;ies,at least for the region southeast of MakushinVolcano.Such dikes could be the driving heat sources for the hydrothermal systems along with possible shallow magma bodies located immediately beneath the caldera region of Makushin Volcano. By taking into account the geology and fumarole field locations,three suspected vapor-dominated hydrothermal systems have been outlined on Figure 14 as being within this northeast oriented zone.All three suspected systems trend underneath the Makushin volcanic pile toward its center along faults from the active fumarole fields no.1,now 2,no.3,and no.4 (Figure 14).At these fumarole fields,the vapor appears to be rising fairly vevertical near the surfacealongnearverticaljointsand/or faults.Such.a'vertical rise could beoccurringfromdepthsofseveralthousandfeet.Below such>depths,the vapormovementisprobablylateralaswellasverticalspatealytPree? ;/eeeooeitfe,re *7Withrespecttothesuspectedvapordominatedsystemintheupper"eeier Valley region (Figure 14),probably the N35°E fracture which trends toward fumarole field no.5 (Plate II)is the surface expression of a recently intruded"dike-like magma body which could be driving the system.©'The N55°W trending normal faults which bound fumarole field no.2 could represent,along with the othernorthwest trending faults in the fumarole field nos.1,2,3,and 4 areas,dike-like 'magma |bodies.Such magma bodies could also be driving the ees vapor-dminated systems.In the case of the vapor-dominated system which includes fumarole field no.1,a large east-west structural trend into Makushin Volcano is suspected.Due to the lack of any evidence of geologically recent volcanic extrusions in the northeast oriented fumarole field no.1,2,3,and 4 zone,it is strongly suspected that!any heat sources would be at depths of at Tae 5.least several kms and/or located laterally into the Makushin volcanic|pile by atleastseveralkmsfromthesefumarolefields.soe oO Four geothermal drilling sites are suggested within these three vapor-dominated hydrothermal systems (Figure 14)where deep directional drilling (up to 2 kms)aimed toward the Makushin volcanic center would be recommended. These sites have been listed in the order of their resource potential.Drill site no.1 does appear to have the best resource potential as based on the gas re Loot ®y.uO /we yi oon .ac?;fo 79 -: fd f ©;: : }"44,fs 're Oe ee ee sr a ne c ote wha roo fy elte:fs a /'. .aan ep ee”oe ae ee ee io °we fs ")y . 'geothermometer work by Roman Motyka and as based on the high silica contents of rocks relative to other unaltered volcanics and plutonics of the region (Plate'tv and Table 3).J Such "higher silica content"rocks suggest the possibility of"hotter"heat sources in the suggested regions.Drill site no.2 was given a high second priority because it lies along the northwest Makushin Volcano-Point Kadin rift zone which has also extruded some fairly high silica content volcanics.Drill sites no.3 and no.4,a region originally suggested by Reeder and others (1982)because of logistical as well as resource potential considerations,are located next to fumarole field no.1.The structural setting of this region makes it an interesting geothermal exploration site."'es ,Va Feo.CO pahe 6 fe ME CP GOS, "Vapor-dominated"hydrothermal systems might exist in the fractured Unalaska Formation and/or in the fractured plutonics that underlie most of the unaltered volcanics of the Makushin Volcano,as well as in or near the actural Makushin Volcano conduit system.Drilling into the N35°E Makushin rift zone could be technically difficult.Northwest of this northeast rift zone,one to four kms of unaltered volcanics exist on top of plutonics and/or metavolcanics as based on gravity data (Figure 7).Drilling through this unaltered volcanics tate would also be difficult.Yet,based on our geochemical isotope data,the yo',./PadMakushinvolcanicsystemdoesappeartobe_one large system having one lar eden ye"pH Satmagma_chamber between 2 to 20kms_depth.The temperature gradient for the >immediate Makushin Volcano region would be expected to be quite high (as Ave, partially substantiated this last summer by Republic Geothermal,Inc.).Thus,"* the possibility of large vapor-dominated hydrothermal systems underneath the Makushin volcanic pile (i.e,the "known geothermal resource area in Figure 14)wae .A,.4shouldnotberuledout.2--°7°:te mo of es "4 4 . -"we. .ar .a oot 'vosae*.7 ye /a 'ON ew ra és : The "area valuable prospectively"has also been included because small ] vapor-dominated systems most likely at depths of 2 kms or more could exist in fractures within the plutonics and metavolcanics of this region.Hot rock and some vapor transport at fumarole field no.8,a geologically recent relic fumarole area in the upper Nateekin Valley,and fluid geochemical findings for hot springs in the upper Glacial Valley all add some support for this possibility.The significance of this consideration is that,for example,the cost of drilling a deep vertical well near Sugarloaf Cone using the driftwood air strip as a supply base would be substantially lower than drilling anywhere -80 - in the "known geothermal resource area".But,the resource potential of the "known geothermal resource area"is,without question,much higher.It is seriously doubted if any large vapor-dominated systems extend beyond the fumarole field no.1,2,3,and 4 region (i.e.,beyond the "known geothermal resource area). Outside of the "known geothermal resource area"and the "area valuable prospectively",vapor-dominated systems are possible but unlikely due to-the low-siltica-contents of the geologically recent-volcanic centers.which.suggest cooler heat sources and a deeper mantle magma source.In addition,there is the Tack of any solid evidence for the existence of vapor-dominated systems in this region. ! av .sO ,ol F «i?ae AfWu,a oA a pee fod Sie r, 'lg fh &*4.whe ft* .i oe /-.é word -' y rad &"\wg Fa +/f._ 4,7 -_«">t woes ft AG 'vy <f - ?"& ;3?.Fs : "why'ra ,nw:' aX Aw t ,/F .eon -_ ''teh git ¢ ,eo ,> t '"e ef ' .''ar f fila ° é ?aveté '?' -./. é foots /.:/ ta ='7 ** to=-weed ."sy ,a om fae we BAS 4a 7git a3 7).F A .vay " "weg rn we mE:ae A eCor wriatlyp Pera preod:ac ws , ,on -e/ay a _¢+call ?- eo ,to p---poe Fa e goley Cr f of :f "6 "27a" .woe ' ,s ""Oerd, -81 - References Black,R.F.,1976,Geology of Umnak Island eastern Aleutians as related to the Aleuts:Arctic and Alpine Research,v.8,no.1,pp.7-35. Cameron,C.P.,and Stone,D.B.,1970,Outline geology of the Aleutian Islands with paleomagnetic data from Shemya and Adak Islands:University of Alaska Geophysical Instititute and Department of Geology,UAG R-213,152 p. Drewes,Harold,Fraser,G.D.,Snyder,G.L.,and Barnett,H.F.,Jr.,1961, Geology of Unalaska Island and adjacent insular shelf,Aleutian Islands, Alaska:U.S.Geological Survey Bulletin 1028-S,pp.583-676. Godwin,L.H.,Haigler,L.B.,Rioux,R.L.,White,D.E.,Muffler,L.J.P.,and Wayland,R.G.,1971,Classification of public lands valuable for geothermal steam and associated geothermal resources,Geological Survey Circular 647, 18 p. Kay,S.M.,Kay,R.W.,and Citron,G.P.,Tectonic controls on tholeiitic and calc-alkaline magmatism in the Aleutian Arc,Jour.of Geophysical Research, Vol.87,no.135,pp.4051-4072, Mahon,W.A.J.,Klyen,L.E.,and Rhode,M.,1980,Neutral sodium/bicarbonate/ sulfate hot waters in geothermal systems:Chinetsa (Journal of the Japan Geothermal Energy Association),v.17,no.1 (ser.64),pp.11-23. Marlow,M.S.,Scholl,D.W.,Buffington,E.C.,and Alpha,Tau Rho,1973,Tectonic history of the central Aleutian arc:Geological Society of America Bulletin,v.84,pp.1555-1574, Minster,J.B.,Jordan,T.H.,Molnar,P.,and Haines,E.,1974,Numerical modeling of instantaneous plate tectonics:Geophysical Journal of the Royal Astronomical Society,v.36,pp.541-576, Motyka,R.J.,Moorman,M.A.,and Liss,S.A.,1981,Assessment of thermal spring sites,Aleutian arc,Atka Island to Becherof Lake -Preliminary results and evaluation:Alaska Div.of Geological and Geophysical Surveys Open-File Report 144,173 p. Nakamura,K.,1977,Volcanoes as possible indicator of tectonic stress orientation--principle and proposal:Journal of Volcanology and Geothermal Research,v.2,pp.1-16. Nakamura,K.,Plafker,G.,Jacob,K.H.,and Davies,J.N.,1980,A Tectonic Trajectory Map of Alaska Using Information from Volcanoes and Faults, Bulletin of the Earthquake Research Institute,Vol.55,pp.87-112. Nakamura,K.,Jacob,K.H.,and Davis,J.N.,1977,Volcanoes as possible indicators of tectonic stress orientation -Aleutians and Alaska,Pageoph, Vol.115,pp.87-112. -82 - Reeder,J.W.,1981,Vapor-dominated hydrothermal manifestations on Unalaska Island,and their geologic and tectonic setting:1981 IAVCEI Symposium - Arc Volcanism,Volcanological Society of Japan and the International Association of Volcanology and Chemistry of the Earth's Interior,pp. 297-298. Reeder,J.W.,1982,Hydrothermal resources of the northern part of Unalaska Istand,Alaska:Alaska Div.of Geological and Geophysical Surveys Open-File Report 163,17 p. Reeder,J.W.,Economides,M.J.,and Markle,D.R.,1982,Economic and engineering considerations for geothermal development in the Makushin Volcano region of Unalaska Island,Alaska:Geothermal Resource Council Transactions,v.6, pp.385-388. Scholl,D.W.,Duffington,E.C.,and Marlow,M.S.,1975 Plate tectonics and the structural evolution of the Aleutian-Bering Sea region,in Forbes,R.B., ed.,Contributions to the geology of the Bering Sea basin and adjacent regions:Geological Society of America Special Paper 151,pp.1-31. Streickeisen,A.,1976,To each plutonic rock its proper name:Earth Science Reviews,v.12,pp.1-13. White,D.E.,Muffler,L.P.dJ.,Truesdell,A.H.,1971,Vapor-dominated hydrothermal systems compared with hot-water systems:Economic Geology,v. 66,no.1,pp.75-79. -83 - APPENDIX A FIGURES Fqua/breaSchurdtMel Veint$ Ny .Northern fark oF Unelaska Islanol Bleska figure / N Egua/AreeSchm;de Mel @ %o Ww Ee! $d.¥o i t 'Faults | |Mocthern fact y2 |os \Unalaska Tslaad 30 40 Nn N Nortkheen fact eS "JD -10 Knelesha Llano #0 |Ejuel HeeaSchmidtMet 'p 2B0 feareeeewadsn220 "210 -200 , 190 160 150 140Figure4,Observed lengths of lineations of the northern part of Unalaska Island,Alaska AZiMUTN OF MARI MUM nORIZONTAL STRESS LOWER QUALITY emma |HILHER WULCANULS &VULCANIC FILLOS .@ CALE QUATEW NAY PAULTS Se. / peek eg a roof ac poum 2bjet? 09 C EE |10Q0 AM | ! QM Map of the late Qualernary leclumie altead Crajcclurics Of the Aleulians uud Alaska.Data in Tables b and 2, Slices trajectories (plippled dines)represent averaged directions of MUG of odfaas,which can be vilher o,oF oy. Situuua duuble line locales pppruaunate Luuadary bebween compressional (ull.¥,)uid caltenmounal (adie -uy, wv?ty)declome dlreas helds,Open arrows:directions of mution of Vacilie plate relative du North American plate (Minstia ef al.1974).Squate and her show the euicenter and B axis of an earthyuake of normal fault type (SYKES and Suak,1974).Ch:Uhirthov bosiotta. Sl er Wa kKamura efal,/VE2 ¢ «Progile 139°Countér clockwis e Sram Lue fast Prof (3S ee ee ;Unalasha Island Ken &3 .Md Nw 8Sow'DS >.\7 .i YSeLitojf;Rosi M x 1|orto Ag NS iN .\ S y S\\gb NEOUS ve 7°vo ns\FP esd RK.'5 Ni N wsPoNg9SyyoN:res 7 OD ="de han ©8 »N x ...{en x vx»6 've NN Y 8 .:j Ny [o)oe onweRONISNEFae\oa o 1 -Y eo”'2 \/;|yi /::ONE neyional m ic)on1”'s 0.-:':\e]':: ; 8 0 eg 5 0 ot 0 ao .LL imne f,J ty 4 |to i 1:rd i},fa :rideeeetheoreticali:|; ,i |:pa mot|oy a !ud : ':'af:y©©,Observed ey J)|.-|i!fer 'be wence o$Untlas & -10¢4 oh ¢sitered |gedit 7 oYit albered/mera volcanics ,KM CS rontal distance)'|pelt oor!i Melereletae =>an ae ¢or ;:ra ';wget,:mo a re go.2 b ane 118 ae ag i 30 37 38 42 1 i {1 ame |:pe b n bu ' . ; . :fotg ot t i ,Unalleced!L}-:|ye :{ie 5 Voleagies ©_-7 279 al |i 4 a ne .i i.PS hue . i :i i \2.65 Feat 4-__ant g :ba4ai .ro rere kM oi Grane deg pite he 2.97 ankf i ''A 't , ."ce ' : ;ae Quacte 'Mor 2edionke QuaetMenard vvite branodliorte Gabbe? 6 4 i 2.90 |Lo!ebabbeo 'to oo w a ot lean;to : "ae |2.80 Cheenie)Pan jd cad w ' \Hecras Li ;-piiiy to ii ,:\*"$4 Duarte ,: \Pairs 'i '\1 y Monzodtoribe i i ;| °a)'j 1 '!MeTaarelewnt.;andr bys ee | vee bebbeo ao ie olGravelerstec;;a]':1 l 1 \|i].: a :bani i L,roy |a a |pp |!Se ga ! ot :hos "Metaveleantes nl1.61 ag :."en ||aeaenee :brane reanekepp:-_i tod 'pa ' 'y '''|7.'.to |;,boa | ,te i Talwene 2-2 .;aan |Mode/ i i i :'1 : gravity Prog ile v0 frosOFO counter clockwise Fram lue ,fast,through Fumare/es on SE srde os Makashin Voleane ,Analasha L3hinod +20 - ¢2 : _icw,¢a><=OP :foo ae i |i ;! -(6 « : mo j foe j | ..i ve!Da Soreree8 1 sare theoretical ;beg S|y-25-dor duby 4 .rr rr :o oO .obserced .;i poo pb en on oe co :mod ! 1 + pet a :oe reeere;'potadtiae i | Phage .::er poe fh ot |i Ptr |'!!aa : i};'7 |Po { voto pak i Loe :eb eeheboro: pot iKMChartronte!olistance vd oS )te an ad,a Fg | 0 +te ae ,ay 28 32 76 ”e Unelbered Velennie (1)|yoy Rg palteredl velenn e 1 -ag?|2.30 -;:.;;7 4 i :: Sd :r . -i -2.57 Unallered wleenie, .ee ee ee .:yd2.67 oo po!an |.|!/|pitercd Uinalesh ftw !|an Biteced Metovelcauar an df,Hitered Mellaveleanre')iti if i)ae <b naleshe |Granediocile °"” andge ti 8 _ | 2.67 we Yu Crane digrile 'ot "me z ,7 7.90 %i oy!rr iy 2.77:Pht se ba Quartz Monzodierile .km 7 |}a -a ee bobhe Hor$els anff, a is | of QuartzMonrodioritt { .oh : 6 ":: ,1 :|os :i "J i.Talwanc 2-D model PE,pe tbat oo fo MIT fa doug .an .: +Captains Ba PlatonaflerMichaelPeodit or Deewes erta/, oO Mekashin Ve leanne Olutan aSéer Reeden 60 Granodyecité Gran:te 40 Quacla Ruaclz Monrenitd Dioerte Quarle Me ozoedserte _-s \__APlas:hd Mon zodttette 55 Maen peate os 90 IX:Seld spac UNALASKA ISLAND "u-lTaR-/ U-20/-k1 6-38-b-/UNI] Qe 18b-f-1 _.eo U-208-R-l oO )10 ISmi n a 1 j O T a T S 10 !58 20km a>Figure 7 Na»O+KoOA 6.0F 5.0r & 4.0F A S.OF-l I |"i | 48 50 52 4 56 58 60 SiO2 Higuce JO co |.60r |.SOF- 140+ 1.30 1.2O-- 1.1O-L NoVU1.OOF BOF Fig 10b lO A A A A La l ae l | 0.8 0.9 1.0 1.|1.2 1.3 TIOe , fig We I6F l l LO f.] Ko0 l2 §3 L4 15 6 vlwi200}- 6OOF SOO} 400} 300}\\\60O0F 500+ 400+ 300+ 200F yaN ya "V6 ure 12 A A I I i | A A !)1 Oo Th tae 13 SAS)easFNC x4: i, CORR ete. 'GEOTHERMALNRCE”AREA | OWN 'RESOU vu"byvy é KN aRpix|2uw)h7I.ps TT . i) 476%ad{AVING SOME=f JAREA -VALUE _ 7>y:er VgPPEesyon heb - . Chow Figure 14 Proposed drilling sites hydrothermal systen.vapor--dominated"Suspected region of a " APPENDIX B TABLES CHEMICAL &GEOLOGICAL LABORATORIES OF ALASKA,INC. P.O.BOX 4-1276 TELEPHONE (907)-279-4014 ANCHORAGE INDUSTRIAL CENTER Anchorage,Alaska 99509 -274-3364 5633 B Street ANALYTICAL REPORT FromAk.Div.of Geological &Geophysical Surveys gucy Rocks Address Anchorage,Alaska _Date October 39,198] Other Pertinent Data Analyzed by SE Date _November 5,198]ab No.9335 REPORT OF ANALYSIS ROCK SAMPLES UNALASKA ISLAND,ALASKA Samples received October 30,1981 SAMPLE DENSITY,grams/em3 @ 20°C 1-R-81 2.707: 17-S-1 2.758 502-R 2.713 -86-R-1 2.851 ,99-R-1 2.815 Q1-R-]2.768 »500-R 2.700 .U-93-R-1 2.861 - 91-R-2 2.752 © Table a JL & wwe CHEMICAL GEOLOGICAL LABORA IRIES OF ALASKA,INC P.O.BOX 4.1276 TELEPHONE (907)-279-4014 ANCHORAS Anchorage,Alaske $2502 274-3364 5 E INDUSTRIAL CENTE: 633 B Stree: ANALYTICAL REPORT From State of Alasxa-Dert.ci Natural REt.,=Product __Fock _ Address __Anchorage,AZsh3_Date _Sertemer16,1952 Other Pertinent Data Analyzed by SE Date Septewer 17,1982 p34 No.483 REPORT OF ANALYSIS ROCK SAMPLES ANCHORAGE,ALASKA Samples received September 16,1982 SAMPLE SPECIFIC GRAVITY,an/@r U-210-R-1 2.73 U-173-R-1 2.69 U-194-R-4 2.67 U-194-R-3 2.81 0-143-R-1 2.84 29-R-81-M 2.59 27-R-81-M 2.60 23-R-81-M 2.75 U-186-R-1 2.78 U-192-R-1 2.78 U-6-38-6 2.10 U-G-45 1.43U-34-S-1 2.68 U-173-R-1 2.67 U-G-27-1 2.63 U-194-R-5 2.77 Table Ih CHEMICAL &GEOLOGICAL LABORATORIES OF ALASKA,INC. P.O.BOX 4-1276 TELEPHONE (907)-279-4014 ANCHORAGE INDUSTRIAL CENTER Anchorage,Alaska 99509 274-3364 5633 B Street ANALYTICAL REPORT From St.of Ak.Dept.of Natural Resources proguct Rock Address Anchorage,Alaska Date October 26,1982 Other Pertinent Data Analyzed by SE Date _October 26,1982 jayNno.__828 REPORT OF ANALYSIS ROCK SAMPLES UNALASKA ISLAND,ALASKA Sample Received October 26,1982 SAMPLE IDENTIFICATION SPECIFIC GRAVITY,gm/er ERROR +,gm/om? U-N-4-82 2.52 0.04 U-N-7-82 2.69 0.01 U-7-R-82-1 2.69 0.01 U 7-R-82-3 2.59 0.01 U-9-R-82 2.69 0.01 U-11-R-82 2.72 0.01 U-13-R-82 2.75 0.01 U-18-R-82-1 2.76 0.01 U-22-R-82 2.83 0.01 U-25-R-82 2.66 0.01 U-28-R-82-d 2.45 0.01 U-31-R-82-a 2.63 0.01 U-36-R-82 2.77 0.01 U-42-R-82 2.48 0.01 U-61-R-82-1 2.90 0.01 U-61-R-82-2 2.79 0.01 U-62-R-82 2.85 0.01 U-63-R-82 2.86 0.01 U-73-R-82 2.82 0.01 U-204-R-82-C 2.73 0.01 U-206-R-1 2.71 0.01 U-207-R-82-BI 2.87 0.01 72 h/e 2 COLUMNfPodes fee _u Nered cltan te ecks.$Mnaclaske Leland oe ;I.Keeder -weiter®LdNeLya) ?NSwsi 2 3 4 5 = 6 :3 heck Semple.|Percent henrent |Percent hercent |fereent 'heecentyage|len tiea number heneceyst \plagrcchse augite Aysersthend chvine |Mise,Name «pphed a nan Been naee Reeee ee eeeee | Z \Lf-/4 -fe 37]E.|&|16 a 4 1 i oJ ';(Le |e(TIT 77h -/-bH ALG.the IZ,ee Ae ca ed4wan : oe fe _-iy U -.oan rtd mi 4 !ol .olivine aug le noun bytowmte|iif iis |e!pit | besall TE se SE ee ene ed eee mote dt|-A ale:|ius:;i23U7RAH|Bel ee |ee Le pe ene ee Sty oceememeee Pot PE a |olrvin'augele |.bytownre et oidi'a i. |basall can hid een |'iz rn aun {|rH HELL |al :: \rr tS r i aWs.|u-6-27 |Bagi l |ele LZ Aw boil teae-|ji!i!magn exste :-i hypersthene augite Z ande sing pido f i asallrc endes fe ii |i i : 't i 4 '}in ||1!i oon -_|-T !toy j +t :3 Z a-G -3E "fp BZ 142 Hl /:i Ti |i i |Of¢€ 4 t j i 'oy i !i i ee tT||an |i”'||itt ray efile||angi te andesite .4 bratlorite?||fy i |i 'ijotietddsine|iy 4 it dy |ate |Sty fa =Foye "Ws :7 i anaes ;SCZ |U-6-75 RUB |Ae ||A Balt |esgay:4 T +r |||oe ee i ;{ug FE bypersthene labredorted 2}7 i |4. ,7 Tj'ac Ee :andesiae i | | ; __1 i |33.|@e7-5-2 |ese eel 1 Vell ass |ose||pte a Tdjp...-4 Aypercszheat.olvne 1 '|__mapretile :: ;.i y :1 :;Jaugilebasallre7labrederite|Hrd ':i |andesife Et!|Vit ee : Ho vo reth ty |mbit boot a |ii| 12 |&-98-o-/44 &2G ines [ye ||}Ze.|asi =rd ;a |ae 4 ||||i ':!_Ie 'rie ¥,¥|eagete elivine.|Wlebredonide |tt ||=ee ee ;7 +T on T 7baselfieandesFeonZ|i!rfid ody ii ft bod i {|i ae -ati +if7toaenalid4iful|it r |Li |1 imaHeeeeeeHee.|Ly --4dt 4.!i aon beta yt ei fd |rs |7 Ty eee ee :i ye a ae --a oon a lable AT _ H !||i | 1 | 1 '\:|4 wrive_Merle for ;;/-,ln)og he.L sli vite»Llas Aa Ng Fovare ca Ata hus _.Velcane megven6 1 rv2 Fhewulu as aré t élesy $me fed 5=3 4 a 5 COLUMNlame efpled feck sample __ leca trea number f Poo, yo -Wier l2 anzures e6sFe | aLy ersthen¢-<. Lae i T . Po!;: | thy estherLMR|LENSE |4 Zi PA |HIF |FEeeapideeeBert's8Wuertedrorite||||Beate|Chad.papas |hadee,,_|eantn 9}-_J A Le 34.22 brithec kes: |[eee oe :ky /Ce!|Ky per sthasaa(EEK ave S| pep ir babbro --| |||parathink|!o :Mo a PLEA ane ee ee -je Quert2 mene herite va | | €.WILSON JONES COMPANY : ' fe /i i :Maer e me r2edret ':; ;; ':i '1 |||t (a ee 4 ! '.t 1 t i] a _i Lk . . 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Use-R-{L (fos R , /00.22|SAITI/S 2614.67)732)fF IAFF 30 |#.AZ Ae eC ne red Lo |oF | uss kal (Ey _®orl livsiloraisdtlowlis tile ine!ig)2ci.96)78.la]|0 aad eeeeeeeeee RETAIN PULPS?|PREP,PULV(4)Wo MIN SEP Z_j4.xs Y ELEMENTS/METHOD;Si02 Al203 Fe903 MnO MgO CaO Na90 K90 10g C0 EASUVARAEEARE ,BATCH NO.33. if te a aes SONOS OF Fe ARSENY,FOL ASEIARE NEEpstTNEBeSe¥Ti Zr V Nb Ta Cr Mo W Mn Pt B Ga In Ge-Sn BYSPEC/XRF W/XRF IADGGS REPT.NO. reuoxo.|S!F] pagwo,|DATE]DATE)DATE |DATE ae Aty83|Si0g |Alp03|Fe203/FeO |Mnd |MgO |Cao Nag0}KgO |P205|TiO |Crg0g he H20°|COs| N)O-OS-R-Lys |P9-2,1S54.2/|7702 |2.69 456 6.19.25)%.421.3.70|,99 |32]22 2 _ §U-bs=R33 L M46.R 20./3 4.211 /9./5|2.46 452 AS 4.501%.6317.291,991,29 93 {403 | U8 -R |L_W47 *®27.93 ieo.rzip7o2l 2.95]B29 |2ev lye |v2 restive 173 |Lys NU=7o-k 2 b Wye *®2292 c179 9912.18 |32074 |2als.d7lsetlzoe|ve bos |lazyay-BVKI L //yg ®60-05 55.6077 £9 364 414.27 |3.73 16-95 |3.481757 1.2)|95 :£2?: "Y-F-R Li jiso_*®22.23 5392117371439 |geal ye [eee 2.5313.86|425 |#3 |£51*\U-98-R-=|Lyst *®92.23 SAS |842 eel 7 t |29 |7s |e 301767 |oe!9s LZ'U-/0-R-Lge 99.99 50.76)2:GI\9.51 |2854)«1 5 |3-4/1 9-6 1 AYE]PS |os |38 J.2h *Urig Rez L W53 *79.92 sis lrisdaen|g9lipe |os8l gosl evel g/l 271407 7 NU 37--Ro|Lyisy ®gooool *|s7alsrigs3|poel.o9 lz eslsre|y¥23|409 |22].7 Laz : O=10RI L//sS R 100.0)55-5 |79 57|2.85)38.20)70 13,95 yy BIS|AP/{e277}A/S 2,70 OU-45-RI Lush L00.£0 19.93\/6.47|3.39 |¢r7|./8 |¥.26 |yz.0914.32 1.77 |vg |3g -.25 U-/47-Ry)Liwjs7 ®99.55 5 \y7 o¢lp20|29 ve loze leog2elecg2l +24 |vs leo _oF _'sek L usB ®22.49 ¢periGotlgos|ses|7 16.69 |e 512,531.3/Ve Le | |U-"SB-R-2 Liyissg ®700.7%48.33 |g o|958|£58.76 |720 \-¥8\2.55 1.57 |ops)27 LiZi | *U1S8-P-3 Ljloo_®27-24 IF67 125.2/'oT|£2 8 |6.97 |o.s7|2c0!62)St 27 1G/'! |V-/60-R-I L Ibo f R 99 14 F205 6.74 3.971 6.97 |./3 2.59 L406|9,5/|.€9 |AS |87 jew | :U=/62-R-1 ;L Ming ®99.79 $5.48 |78.27|942)3CO|/6 |2.2/|9.00 |7.2)|4271.25 |9 !ral 1 U-Ib7-RI L jz ®98.71 60.6)176.2213,59|3.54/98 |1493|7.091 9.04|2.20].4/|.99 |.33 U 173 p-|L Moe R 9945 43.89 \/8.97|4.09|2.64)79|6.08 |\/437|2-52]-F2 |-22 |.9¢|0.0 PREP.PULV()UL _MIN SEP RETAIN PULPS?So a Pas ZL RacKS SEELEMENTS/METHOD:fics Alp03 Fegug MnO MgO CaO NagO K20 Tide Or203/04S (Aya F EEG >Baul NO,3.3 He de Ge uae SATGoCdMa AeRURASTI®)POLMISERE DATEIN 25bADATEOUT | .A /Be Sc Y Ti Zr V NbTa Cr Mo W Mn Pt B Ga In Ge Sn Bi/SPEC/XRF W/XRF IADGGS REPT.NO.___ |FIELD NO.|'No.Lasno.|PAT MAD (SPECI srBC-8 ay ABMs |SiO2 |Alg03|Feg0g FeO MnO MgO |CaO Nag0 K20 |P205|Tide or203)27 Hg0°|CO210-18-22 L Mba ® | .99-75 56.451/7.97|2.34 599 /8 |3.0)"Z.3 3.66)/.44)_.25|/.00 __[o.00 [AHo-K L Yoo *94.63 65.03)1 OS.59 £67 9 219 19951436 |472 |231 |Ze =of H-14-e-L //o7_*79.33 54.801 p70915.93|446)17 14.671 7,7413.32)4571.2/|95)los V=192-(e4 L WloB *®99.35 53.14 4114.05 |£/3|19 7.251792)3-3 vol.371 420 -L/z,NO-1y-3 Li /lo9 RI]99.50\_53.27 \/7/a|F.63 |4-37).34 2:3)|ze7 FHL hes 2 |.9s Las | (UHLPg-RH |Ly70 ®| on3n|_-Is4.9¥7.931 7/21 5/920 leeriealsoslyre'|23|Les _ned =\VIE RSI Ly _-|£2.41 |Shor |pe.214.5F|4.17 2/2 13.32 |Monies7iseo|79 179 |237 |"Ox-1G-R-W EI 72 ®|gs.2si--lae7eliaol2¢|6-63\ye lero ezelass|tele |aa]|-z0 )!\\U-to) R-L 4/72 R ) | 99-16 48.74 |7L09 |02.44 ZH\y9 19.90 |2.0312.341 69 |28 |,35 70%ai(U-202-€1 L i174 R |./ob.0)466 VE63 13.79 sey LB.2.7)Lad 2.350 7a wr,'G7 -1/3U-203-R-7 Loz _*;__|oo.rg|152.62 16.97 |2.35]§.36l.79 legs lees ldise|7724.70 lo?47 | pl/-206-R+bum *|00.981 5501 17.16 s.9|397|26 |3.93 |6.07]364!p col .22 |208 Zl | U-bB-k-|Leu77_*| yoo.n7|_|53.5¢\2.9¢l2.9¢1 eel -26 1 a.alage ls.v2!751.20 |fee 65 _ 'U-208-b-2 L 77g / 0p.28 53.95 |/3.4916.30 |2.95|79 [FLS|BY9|SA |f-07|18 |7.02 £02.|: v-2io-k-|_|7p |oo.5t|(SS.891 pe zolaze|Sol sF ly 341 24/1506 469 28 Ars zis]i Y=OS L Wgo _#| 100.52 S081 \/7$715.89|297|-2/15.731 9.071 3.224531 26ler7i 2:77 ! 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SHIP DATE |DATE |DATE |pate]|,a Tes .M MeO "Tapanl:,207 Ho0°Oe |FIELDNO.|'no,|LABNO.|puLV.|AA-D |SPEC.L|spEc.s|Ste |ABMs!SiOz |Al203/Feg03/FeO |MnO |MgO |CaO |Nag0|'KO |P205!TiOg |Cr203}"7,01!H20"|CO2 (e282 LNG R 99.53 $2.27 46.94 3.84|4.551,16 |6.2/1 24/1289 |ss |.zo |.89 1.73 ue-34 LBL ®99.75 S233 1297230!64417 |oy|959 |3.28!36|ye|00 123 WU 28-h L /Q 7 R 99.42:S2.YS\76.09 12.66!2/oli2/|2.501 5.571 7 50 465 |.29|pz0 '=.08NOG95°4 483 *Lo0.45 6303 |/6.52 -4:50.76 |2s5\428|3.77 2221 .7y |.czl OS «26 -.:e og 65)2,Pa 'e5-4-6 L WBF R 7002 Sobel /975 307 £221:/o Re 77 "|47:78 £8 /3 BS \.Wd . . : a ; ' .mi 4.33 Ae 79 26 ./4 62SU-2-S-/bilgo_*/10.46||63.03 |/g.82 2,221 9.26 le ase a2 a hl 10-84-84)Log)®200.9%£7.08)17.22)2.84 |4.75 8 |3.96|7.491 3.9)|154 |25 |.Fo L Ak 136-4 Liz ®yoo.84||sze0ls2771 2.751 4.9/|27 |voe|255|3.05|s72|5 |290 .6F | (U287-S4 Lids &®eops|'>02.22 St.22|s25¥13.96|3.92|./9 |v 9/|2oolZsals¢2!79 |97 aEE'S \U-4S-S-]hwg4 ®_ £00.83 OL24 |e481 3.241527 7S |2931896 1556)2s ||v5 Lb |t|U-SIS-3 L OS R 700.47 5.35 19 56 SLY 182 229 1 7.oS g/7 3.421439 |.23 |.76 46 !;{ te sy-S-/L WG RE 99.56 6212 |2¢.%|£92 |3.56)75 |750 |4.96 |¥-78 |7.02|25|80 LF, LSS)Lyg7 oat SS Hlo |p FIN 2:99:92)2 |04 ¥.22/3.56)772 |627).95 103 Lt\U-S9-S-}Lyge &®28.72 St obls7$3 15.24 |yo/|s¥|2031755|2.70|wee |34 |£06 182 || |i R |_oe os od I.L f Avg Sales ©ALY |: L R ) " ! 7 L R , Yl see ' , ' ES .6aWe |ra ,ae Ze i mar rel ieee KBE DEINae- |(|Nand Ky20.To;%Mno zr0 |erasEoTITRAL RICE3 5 4 oe I.C ai 7 ae an Ay Niele:BATCH NO.7-Rb,20 S10 LOI 1 ,0-!a-anA IMETR c,!qe oe Bt aa rc "Ane!OTE ING/LYKLDATE OUT 2 273 273 eeosLoNO.)LAD NO.|sidc{al,octre,o;rob noe ae Hage -r 195/288]no 2awb nosey.a me blots pa :i|3 !: | | "Be aleSBA |vost ozo aebl sled ize shih veal abel ood cvel oval:hoot abel |pit 7 BB-C LSB roe pez]2.03]gio veol_siey|acl neal 2791 027132)i Lav avel [piel TSU ILSS234 [esd real ae3l abl con vlog 9s]btel wed avd ors it}el ibe aati tty sli [oe ig / eng]2.80]°|/.|elf asl nyo]|goyfie et ST LS82S Ki eyai isis sas]ried aeel_o'7s|373l rst 272]aril oi)iL Lb cog!aazl |pagal |(a SST esebe #2400|HN 7S bib2|8294-7267 254 y76|.092|ars ovel Li lit |bE bazol eazy]=|969 :fo SoVESY2T WN zed]687 ze9|22]72 ors]2.80,cel on _ol7 al!|ti |av7l age 9M o-S-\ILSS2ER |se oa ln35]e75|#94 3921 762-2967)744)vel apa oni t Lose l.goe Sle 10, oeS-{ESR Regzsl pe.03]aw SMI £36 _bhi 1 yl |ole"£06 OVA azo]0.06 |046 (Ade 9 S797 LSEBOR [50al iar]gas]diel coy)eldel!Yoel ae ::2.32|0.97||igael |tSTESS3)Keo sol ig zol peel eed £60 glial #2:oieel 0-79]aeal-agl.i ||i aol as EY _._g :'':vwereQO272::,!ar)>:-_:a 1 ot at ,toaed2CSRELAA535)752)352)143)473)2:32)291)OF7)026)O78 ||O13)Os7ol_.Say "TG, Nb>ES¥24 RI,SQ (6.27)$11 |315 S733 6S833 Rey o6|yea]pro]223]3/|66)15)299 098]adel orz7]i bose |-2.e7 Saf,9. .j x j .io sotas oo.7 rn ;rr ar a a:SsuD:u 6 SSH iK C201 LAT)2 69|233 1.00)BPs 2b 44 bool ofl o25)oh:|.0/8 |Ocf 529 72 eke y -ae ery)ee Pane |(S-]IL SS3S5KI eae I745|ko]Gell g22|R125"2.77)0¥Z|403]930]0/9)"':/.02|1,40 993 vei -. - Q | ,;;i.|.T->-f [LS83LR'4 33]p23!o.p3|cod cool ebol zeal o97 sos]ale|-ae|-094|0.4/7.38 2 i3-RESET Rye.50lle.0e|697]254 261 |vile 2.61|alto oeal arzl aie]aoe |os2l |eer fon pl iele ci ow 2 '::.':. 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(75 S/he K Jindicetee 1 | (53 S$)|b K Bde,Zs F a 6 9-S-Nb ;ode E , (-85°-$-2|L K Dvetlie.ts ' flea K Shen Gie ?M1 (-555-7 \b i Dacets 2 " ares £7)|b i nine be CBaeecen )ty 0-80 -©[IL KR Arb ads 4 (173K R Bo we thee 7 HR 3 i Bnvcaticc | i "15 -Rl |im Pnccalis,. :_ IQh-K-/Lt Por citee Fe Calor,LL,_.rithm! a?ee ae |L!AAVOUCUICa l J dv 7 AVA \3/'Vc No.Samples 2 0 ems "e - ..a ”> abst oo wo nee .. Jehea Ut,At PEK BATCH Nt / ip so.LAB No,[BME)Bale ANALYSIS DESIRED CEOL/PROJ.Darin |BALE oR l,.A /L nbivveca ve Vo Cons aa Paid Jbin ©4 Lee wana Lowe Q,Labkeo ) :aaa Perce Coe Cella Ce |Loa Oet)aeWwNamtsNN!\N°7=>™>'Ee ox L,A \E cael tid -l Jy iz a v (7?,is Aina ad "ee 7 Gertie,&E \' a - >7 ;|6283 |v fh l Lawalex | 7 '|(oo a L N\An,wales .|Vv i Zz aloLE SEL c . , « ; Lu ea eee 7.le.FE.' ;1LCwreOotea -_nuv!7>chxjo>7-4 '-S/al I,A ka L 7.22 tT SiO»LDGO SiOz XRF Na20 LDGO Na20 XRF MgO LDGO MgO XRF Sr Ba La G »b $-38-8-1 59.5 59.5 4.55 4.50 2.50 358 544 16.3 Makushin Volcanics "-145RI 51.2 49.8 2.64 2.32 7.20 8.26 576 225 8.8 "-173R1 49.1 48.9 2.70 2.52 5.80 6.08 548 225 10 U-186RI 56.8 56.5 3.78 3.66 3.25 3.61 391 461 14 M-201RI & 208RI1 52 48.7 2.65 2.34 8.10 9.90 593 225 6.8 Table 55.0 53.6 3.49 3.42 4.19 4.31 410 340 7.5 1 TABLE 5 Lot LuEeF&F XX =Strong XRD es) X =Moderate XRD S ¢& T =Trace woo koa a e2So{uu -ion =-aabeaaoO =egi23SampleTS(Thin Section)/Hand Specimen =m BO 2 #Location Description N-1 Glacier Valley-Kettle Fe-stained till,volcanic rock clasts X xX - Moraine south of Roman's (andesites)cemented w/vein material,camp (Rep.Well #3)kaolinite,&montmorillonite partially devitrified glassey groundmass.Anomal- ous presence of NaCl not verified in hand or TS. N-2 100 yds NW of drill Banded black &orange volcanic tuff,XX site #2 locally Fe-stained seeps.Unit is young Makushin volcanic draped over a high angle slope above drill site. N-3 N-facing slope across Andesite dike with pilotaxitic tex- stream from base camp ture,illite/sericite alteration,plag- Dike trending toward ioclase phenocrysts cracked,minor Fumarole field #2 calcite and chlorite. N-4 Nateekin Valley near mouth Altered tuff called "Peanut Butter Unit".XX on S-side of valley at N-Tuff in vicinity of dikes altered tofacingslopew/waterfalls brownish orange clay.Illite identi- related to dike rocks fied by XRD.Clinoptilolite in TS. N-5 Nateekin Valle Indurated,sulfide-rich tuff 1 to 4 mm(Same as aboves pyrite cubes. N-6 Canyon below base camp Granodiorite,relatively fresh in TS, opposite Fumarole field #1 plagioclase phenocrysts appear broken, hypersthene,augite,and chlorite re- placing dark minerals. N-7 Canyon below base camp,Sulfide-rich float associated with float from same location granodiorite @ N-6.Texturally similartotuff(N-5)from Nateekin Valley. Tuff is indurated due to extensive ser- itization.Fe-staining pyrite,ranges fresh to oxidized.Assay shows low Cu. N-8 Fumarole field #2 Clay from fumaroles.Dominantly kaolin-xX TTitebyXRD-minor montmorillonite/ser-icite in TS assoc.w/Fe-stained areas. N-9 Fumarole field #2 Joint filling collected near sample #8 Derived from altered andesite?Kaolinite dominates,minor vermiculite/biotite ob- served in TS. N-10 Fumarole field #2 Montmorillonite,Fe-stained clay w/relic X andesite texture N-11 Fumarole field #2 Andesite?Cracked plagioclase pheno- crysts-extensive rim alteration."Idd- ingsite"alteration of olivine?Primary biotite. N-12 Divide above Fumarole Pumacious tuff,seritized and kaolinized field #2 oriented vesicules minor Fe-staining. N-13 Divide above Fumarole Fine indurated tuff -dominantly field #2 sericite. Rt 8b SnWwHoAs\Go!NI Fe'My Bo ° ELEMENTS SIDE 1 uPb Zn Au Ag Mo ¥ a 'I ELEMENTS SIDE 2Geant 1-AKS"METHODS)iigeKAP ,Qe ESPEC,,neAton BATCH NO._S94 SAMPLE TYPE_ _pate Ins4b2 pate outSY7/geindadPTEUy¥2p |7BaBoBICdCo|pee |others:_SEyitie "BrlOP'"GALT.LAB SHIPMENT NO./DATE -We wy,il |Uy.vec a oO LFUF te tp at Ot a"-FIELD NO.LAB NO,Cu,|Pb.|Zn,at Agi I se 4 W Hes ;a:Co;Ni |,Fe.|°Mn Ba |Be |.Bi Cd Ce M-s.fn 8646R}391 /2 |sy lela;¢1:2:le].aE ya ee A-7 [L ee4ut RI ft [25 |/osle.l fe.Zilzy efi y . :uy are a ae Dy bs vo : ti.or cep yrrdhfeba!7 4 = L i L ake ;Tita PGi ps L )ww ";,.:i” L ;%7 i : qL "Le i L 2 '- 'L..,meres 4s eae atte i y ;'i 4 ;i 'i L r 7 vi :|ee ees ee L :ft ;. L !ii ' L :" L (2k A le Us L ae Ce A rr 1 besides : Pop ke ca ae .pid :.' L met csp pe :Jo |°ge oh eee,"eee mpgs >fos sginiren:ov saeee 'p e .say!votcan ll { . eens rears Te (utp ifs ts»GEOLsPROVEGT Cle Micke /unaie!U-N-7 -&2Z ;be 'i os ne ae fi APPENDIX C LETTERS vr.Clay Nicnols UNIVERSITY OF UTAH RESEARCH INSTITUTE URI EARTH SCIENCE LABORATORY 420 CHIPETA WAY,SUITE 120 SALT LAKE CITY,UTAH 84108 TELEPHONE 801-581-5283 August 10,1982 Alaska Division of Seological and Geophysical Survey 3U01 Porcupine Drive Anchorage,AL 9950) Dear Clay: After trying to reach you by phone the last few days I thought it best to write you regarding the samples you sent for dating.The following is a list of the sample numbers and my recommendations: U-6-27; J-91-R; uU-93-R-1; U-120-R-1; J-152-K-1; U-192-R-1; U-194-R-5n; U-201-R-1; U-2U8-R-1; U-210-R-1; Separate plagioclase phenocrysts to date. Altered,whole-rock date would give minmum age,I wouldn't date this one." Plagioclase altered,calcite abundant,don't date. Olivine completely serpentinized,could yield minimum age on a whole-rock date,a fresher sample would be much better. whole-rock date. Olivine completely serpentinized,plagioclase might yield a reasonable date if it remained closed during cooling. Wnole-rock date. Plagioclase could be dated here. Whole-rock date. Olivine serpentinized,plagioclase could be dated. ° All of these rocks appear to be fairly basic,basalt-gapbro (?),so dating plagioclase very low in potassium could be a problem.If you have pulk chemistry on these rocks it would be helpful in deciding whether separating plagioclase would be worthwhile. Letler 7 If you have some compositional data please call.I will begin processing the three wnole-rock samples now but will hold off on the others until I 'hear from you. Sincerely, Kaw Creer Stan Evans SE/jm Letber [ UNIVERSITY OF UTAH RESEARCH INSTITUTE UURI EARTH SCIENCE LABORATORY 420 CHIPETA WAY,SUITE 120 SALT LAKE CITY,UTAH 84108 TELEPHONE 801-581-5283 September 27,1982 Dr.Clay Nichols Alaska Division of Geological and Geophysical Survey3001PorcupineDrive Anchorage,AK 99501 Dear Clay: I have completed running the four samples we decided to try.The threewhole-rock samples (U-152-R-1,U-194-R-5m and U-208-R-1)all failed to yield any detectable radiogenic argon as mentioned in our telephone conversation.IrecentlyranaplagioclaseseparatefromsampleU-6-27 which unfortunately also failed to yield a detectable radiogenic argon.Based on the detection limit of our mass spectrometer I would speculate that all these samples areTessthanahalfmillionyearsold,possibly much younger.. I regret that all the samples failed to give any age information but this is a risk when dealing with whole-rock samples which are very young.The plagioclase separate was a bit of a surprise,usually you can pick up some radiogenic argon in a mineral separate if they are over 50,000 years old. If you have any questions regarding this work you may contact me through ESL even though I will no longer be with them after the first of October. Sincerely, Daw Grark S.H.Evans,dr. SHE :jp Letler 2 APPENDIX D PLATES fou\i RECEIYRE REPUBLIC GEOTHERMAL,INC.|,rmotnasg MEMORANOUMuoci foe ly Oy TO:G.W.Huttrer March 1,1982 FROM:D.L.Carey(1 ¢. SUBJECT:Status Report on Land and Regulatory AuthorityInvestigations,Unalaska Island -Alaska Power Authority Contract Per your request,the following is a summary of the re- sults to date of our investigations into the status of the lands and regulatory authority for that portion of Unalaska Island of interest to the Alaska Power Authority (APA)lyingwithinthefollowingtownships:1.72S.,R.118W.;1T.72S., R.119W.;T.73S.,R.119W.;1T.73S.,R.120W,Seward Baseline and Meridian.Please be advised that this is only a summary,anditemsnotpertinenttothequestionsaskedarenotincluded. Also,this report is preliminary in that all of our detailed research has not yet been completed and additional material may be uncovered which could alter some of the analysis andconclusionspresentedhere. Factual Background Unalaska Island was placed into the Aleutian Islands Reservation by Executive Order No.1733,dated March 3,1913, for the purpose of preserving and encouraging the development of birds,fur bearing animals and fisheries.However,this order was revoked as to Unalaska Island,thus removing Unalaska Island from the reservation,by Executive Order 5000, dated November 23,1928. The Alaska Native Claims Settlement Act of 1971,PL 92-203 (ANCSA)was enacted on December 18,1971.Section 11 with- drew,subject to valid existing rights,all lands (except National Park lands)within an approximate 25-township block around the village of Unalaska and allowed the Secretary of the Interior to withdraw additional acreage as necessary for native corporation selections.Public Land Order 5175,dated March 9,1972,implemented this section of ANCSA by with- drawing,subject to valid existing rights and prior appropria- tions,"All land in the Fox and Pribilof Island Group not withdrawn for the Aleutian Islands National Wildlife Refuge, containing approximately 2,150,000 acres".Public Land Order 5183,dated March 9,1972,withdrew from selection by the regional corporations under Section 12 of ANCSA all land with- drawn by Section 11 of ANCSA which was within the boundaries Braj.Catt) Memorandum to G.W.Huttrer March 1,1982 Page 2 of the Aleutian Islands National Wildlife Refuge,among others.Public Land Order 5184,dated March 9,1972,withdrew all lands withdrawn by Section 11 of ANCSA and not also with- drawn for any part of the National Wildlife Refuge System and reserved them "for study and review by the Secretary of the Interior for the purpose of classification or reclassification of any lands not conveyed pursuant to Section 14 of said Act (ANCSA)." Section 14(h)(8)of ANCSA authorizes the Secretary of the Interior to convey both the surface and subsurface rights to an undetermined amount (as of that date)of land,but less than two million acres,to the regional corporations on the basis of population.According to records obtained from both the U.S.Fish and Wildlife Service (USFWS)and the U.S.Bureau of Land Management (USBLM),on December 15,1977,the Aleut Corporation selected the subject lands (among many others) under Section 14(h)(8)of ANCSA (these are commonly called""overselections"). The Alaska National Interest Lands Conservation Act, PL 96-487 (ANILCA)became law on December 2,1980.Section 102(3)(b)of ANILCA expressly defines lands selected by anativecorporationmadeunderANCSAtonotbepubliclands. Section 303(1)(iii)of ANILCA defines the Alaska Maritime National Wildlife Refuge,Aleutian Islands Unit (AMNWR-AIU)to be made up of the existing Aleutian Islands and Bogoslof National Wildlife Refuges,and all other public lands in the Aleutian Islands. Analysis Based upon the above,I believe that the subject lands on Unalaska Island were not a part of the Aleutian Islands National Wildlife Refuge (AINWR)at the time of the passage of ANILCA.Also,according to USFWS and USBLM records,the Aleut Regional Corporation appears to have validly selected thesubjectlandsin1977aspartofitsANCSASection14(h)(8)allocation.Such valid native corporation land selections are defined in ANILCA as not being public land.Thus,although ANILCA placed all existing portions of the AINWR and all public lands into the AMNWR-AIU,the subject lands do not appear to have been of either of these categories.I there- fore conclude,on the basis of this data,that the subject lands are not now within the AMNWR-AIU.This means that the USBLM,and not the USFWS,is the agency responsible for managing these lands.Thus,our request for approval to conduct the geothermal exploration operations should properly be filed as a Notice of Intent (NOI)with the USBLM. Memorandum to G.W.Huttrer March 1,1982 Page 3 Notwithstanding the above,the USFWS officials in Alaska appear to believe that the subject lands are within the AMNWR- AIU,or at least believe that these lands are to be managed by the USFWS as if they were within the AMNWR-AIU.I have not yet found a reasonable basis for this belief,although the USFWS may believe that Section 906(0)(2)of ANILCA gives them authority.This section of ANILCA generally states that all federal lands within the boundaries of a conservation system unit (including all national wildlife refuges)shall be administered in accordance with the laws applicable to such unit.However,since our research indicates that the subject lands were not public lands or within the AINWR at the time of enactment of ANILCA,the lands are not within the "boundaries" of the AMNWR-AIU and are not subject to the administration of the USFWS.The question has also been raised about the ulti- mate disposition of these lands should they not be conveyed to the Aleut Regional Corporation (the corporation's entire ANCSA Section 14(h)(8)allotment is purportedly only 52,000 acres).Section 906(0)(1)of ANILCA might suggest to the USFWS thatthelandwillbecomepartoftheAMNWR-AIU should the land not be conveyed to the Aleut Corporation.However,I believe that because the lands are not within the "boundaries"of the AMNWR-AIU,Section 906(0)(1)of ANILCA is not applicable. The USFWS officials in Alaska have also stated that,in accordance with their belief that the land is part of the AMNWR-AIU,they cannot lease the land under the Geothermal Steam Act.They further argue that since the land cannot be leased,there is no reason to explore for geothermal resources, and,since there is no reason to explore,they will not issue a Special Use Permit for any geothermal exploration activities. I would respond that 1)the lands are not within the wildlife refuge and 2)although the Geothermal Steam Act (Section 15(c))does expressly prohibit leasing of lands within a wildlife refuge,leasing is not of issue here.The subject lands have already been withdrawn from all forms of public appropriation and mineral leasing,and have apparently been validly selected by the Aleut Native Corporation.However, there are still many good reasons for the Alaska Power Authority to wish to conduct geothermal exploration in the area,not the least of which is to assist the Aleut Corporation in evaluating these lands prior to applications for conveyances under Section 14(h)(8)of ANCSA.Nothing in the Geothermal Steam Act,ANCSA,ANILCA or the USFWS's own regulations (50 CFR.25,26,29 &36)would seem to expressly preclude the issuance of a Special Use Permit for these types of operations in a National Wildlife Refuge.Indeed,the USFWS,in August of 1980,issued a Special Use Permit to the Alaska Department Memorandum to G.W.Huttrer March 1,1982 Page 4 of Natural Resources,Department of Geological and Geophysical Surveys,"to gather baseline data on geothermal systems"for lands on Unalaska and Umnak Islands which the USFWS believed to be within the AMNWR-AIU. Summary In summary,all the information collected to date indi- cates that,notwithstanding the beliefs of the USFWS officials in Alaska,the lands in question 1)are not within the AMNWR-AIU,2)have been validly selected by the Aleut Corporation,and 3)are managed by the USBLM.The USFWS's contentions that they manage the lands and are precluded from issuing a Special Use Permit are both considered to be invalid for a number of reasons.Therefore,pending the completion of our detailed land status check or the receipt of information to the contrary,I recommend that the Notice of Intent for the geological fieldwork be filed with the USBLM as soon as possible. DLC/wp REPUBLIC GEOTHERMAL,INC. 11823 EAST SLAUSON AVENUE SANTA FE SPRINGS,CALIFORNIA 90670 TWX .910-586-1696 (213)945.3661 March 19,1982 Mr.John L.Martin Manager Alaska Maritime National Wildlife Refuge U.S.Fish and Wildlife Service Homer,Alaska 99603 Dear Mr.Martins: The Alaska Power Authority (APA)has contracted with Republic Geothermal,Inc.(Republic)to explore the eastern flanks of Makushin Volcano on Unalaska Island for geothermal resources.The geothermal resource exploratory operationsplannedbyRepublicandtheAPAwillbeconductedinbasicallythreestages:initial geologic exploratory work,temperaturegradientholeoperations(both conducted during 1982),and drilling of one deep exploratory geothermal well (drilled in 1983). An application to the U.S.Bureau of Land Management (USBLM)for approval of the initial geologic exploratory work was rejected by the USBLM because they considered the area to be under the administration of the U.S.Fish and Wildlife Service (USFWS).Because the lands to be explored were selected on December 15,1977 by the Aleut Corporation under Section 14(h)(8)of the Alaska Native Claims Settlement Act (ANCSA),it is our understanding that these lands were not made a part of the Aleutian Islands Unit of the Alaska Maritime National Wildlife Refuge (AMNWR-AIU)by the Alaska National Interest Lands Conservation Act (ANILCA).However, it may be possible that these lands should be administered in accordance with the laws applicable to AWNWR-AIU. Based upon this decision by the USBLM,Republic,as contractor to the APA,is hereby requesting a Special Use Permit from the USFWS to conduct these initial geologic exploratory operations on portions of Unalaska Island.This request for a Special Use Permit covers only the initial geologic work.Separate permit applications will be filed for the second and third stages of the exploratory work as the details of the operations are finalized. REPUBLIC GEOTHERMAL,INC. Letter to Mr.John L.Martin March 19,1982 Page Two The initial geologic exploration work will consist of geologic mapping of special areas of interest,water sampling of springs and some streams,gas sampling of springs and fumaroles,a mercury soil survey,and a self-potential survey.Attached as Exhibit A to this letter is a detailed description of the proposed operations.Attached as Exhibit B to this letter is a letter from the Aleut Corporation giving their concurrence to the operations proposed under the APA contract. We currently plan to commence the initial geologic exploratory work by April 15,1982.Should you have any questions or concerns regarding this request,please do not hesitate to contact me at the above address and telephone number,or our subcontractor's representative at the following address and telephone: Mr.Steve Grabacki Dames &Moore 800 Cordova,Suite 101 Anchorage,Alaska 99501 (907)279-0673 We greatly appreciate your consideration of this request for a Special Use Permit. Respectfully Dwight L.Carey Manager,Environmental Affairs DLC/wp Attachments EXHIBIT A DESCRIPTION OF OPERATIONS The Alaska Power Authority (APA)has contracted with Republic Geothermal,Inc.(Republic)to explore the east- ern flanks of Makushin Volcano on Unalaska Island for geo-thermal resources.Figure 1 is a vicinity map showing thelocationofUnalaskaIsland.Figure 2 is a map showing thelocationoftheproposedexploratoryoperationsonUnalaskaIsland.The geothermal resource exploratory operations planned by Republic and the APA will be conducted in basicallythreestages:initial geologic exploratory work,temperaturegradientholeoperations(both conducted during 1982),anddrillingofonedeepexploratorygeothermalwell(drilled in1983).This application covers only the initial geologic-work.Separate permit applications will be filed for the second and third stages as the details of the operationsfinalized. The initial geologic exploration work will consist ofgeologicmappingofspecialareasofinterest,water sam-'pling of springs and some streams,gas sampling of springsandfumaroles,a mercury soil survey,and a self-potential survey.The initial exploratory work will probably be con-ducted on foot,although helicopters will be utilized totransport.the field people to distant sites,and three-wheeled all-terrain vehicles may be used if feasible.There will be two people in the area conducting the mapping,waterandgassampling,and the mercury survey for approximatelysixweeks.Two additional people will join the team for thefinalthirtydaystoconducttheself-potential survey. A portable camp will be established at the start in the field area which will include two 12-foot by 20-foot sleeper tents,one 15-foot by 30-foot cook tent,and a portable out- house.The camp may also be used by one or two environmental scientists for one to two weeks during this period.The crew and all materials,including the camp components,survey equipment,and individual supplies,will be transported toandfromthesitebyhelicopter.The location of the camp site is shown on Figure 2.The temporary camp will be in-stalled by a company specialized in placing portable camps in remote areas,and they will be required to minimize sur- face disturbance. The geologic mapping will consist of ground and heli-copter field surveys of selected areas,conducted with theaidofaerialphotographs.The water and gas sampling will S FIGURE2;4 ,WO EH q 3 anay ET TTT A cra _|LOCATION OFVALUHED,Jedi INF iG\|PROPOSED OPERATIONS y \NE ON UNALASKA ISLANDTAY! ar an Vee eratebadNeary: ---en STK =ae be grab samples of springs,fumaroles,and some streams taken with sampling equipment small enough to be carried byhand.The mercury soil sampling survey will consist of taking soil samples of approximately ten grams from siteslocatedinagridsystem.The approximate location of sam- pling points will be the center and four corners of eachsquare-mile section,although some adjustments will be made due to the topography of the area.Elevated levels of mer- cury in the soil have been correlated with the presence of geothermal resources in a number of geothermal areas through-out the world. The self-potential survey is the most sophisticated activity of the proposed initial exploration program.Thistypeofsurveytechniqueisbasedondetectionofnatural direct electrical currents flowing in the ground.To detect these currents,one electrode is placed in a hole approxi- mately one to two feet deep and six inches in diameter,then wire (typically thirty-two gauge)on a reel is connected to the electrode and unrolled approximately three to four kilometers.Every two hundred meters the wire is connected to a second electrode,placed in a hole of the same size, and the self-potential voltage and contact resistance is recorded.The survey personnel will likely be dropped byhelicopteronridgetops,and will unroll the wire,install the electrodes,and take the self-potential measurements as they walk down the eastern flanks of the mountain.The elec- trodes will be removed from the soil and the holes filled after the completion of the measurements.For a more detailed description of these operations,please refer to Attachment I, Self-Potential Survey Field Procedures. Impacts from the proposed operations will be temporary.The majority of the activities will be conducted on foot, with helicopter transport for distances greater than can be reasonably travelled by foot.Helicopter use is being pro- posed in part to avoid the surface disturbance which could result from off-road vehicles.Helicopter operations will be conducted away from the coastal areas and thus will not occur near seabird rookeries.The helicopter pilot will be instructed to avoid any other wildlife in order to minimize the adverse effect from the helicopter noise and movement upon the wildlife resources in the area.A three-wheel all-terrain vehicle with balloon (low ground pressure)tires may also be utilized if weather conditions preclude the use of a helicopter.If this vehicle is used,it will be used infrequently and only where necessary.Emergency transport of injured personnel is one ofthemainreasonsuseofthisvehicleisbeingconsidered;in the event weather conditions prevent helicopter use in the upper elevations,any injured could be transported along the old road from the camp site to Driftwood Bay for helicopter pick-up at that point. -4=- Food and fuel will be purchased at Dutch Harbor to the greatest extent possible.Garbage from the camp will be transported back to proper waste disposal facilities in Dutch Harbor.Grey waste water will likely be disposed through a leach line built by the camp construction company. Black waste water may go through a leach line system,placedinapitandtreatedwithlime,or dried and burned. -5- ATTACHMENT I TO EXHIBIT A SELF-POTENTIAL SURVEY FIELD PROCEDURES Standard self-potential survey procedures will beused.The following is from a description written byHarding-Lawson Associates,one of the potential sub- contractors for the SP Survey.It has been adapted forUnalaskafieldconditions: l. 10. Install telluric monitor,consisting of battery-operated strip chart recorder connected to dipole100mto500minlength,at easily accessiblelocation. Select base electrode location in central partofsurveyarea. In copper sulfate bath,measure initial polar- ization between base,measuring,and portable reference electrodes. Dig hole (1-2 feet deep,6 inches in diameter) for base electrode deep enough to reach natural soil moisture and to allow for shading from sun. Install base electrode,attach end of wire onreel,and install sun shade. Move reel to first survey station.A reel hold- ing up to about 3 to 4 km of lightweight wire is used for surveys conducted on foot. At survey station,dig hole deep enough (6 inches to 1 foot)to reach natural soil moisture and in- stall measuring electrode. .Connect negative lead of multimeter to connector on reel going back to base electrode,and positive lead of multimeter to measuring electrode. Read and record SP voltage and contact resistance. Voltage must be read for at least 20 seconds ifthereisanypossibilityofsignificanttelluricactivity.If short-period (less than 1 minute) telluric activity is seen,voltage must be readlongenoughtoobtainareasonableapproximation of the steady-state value.Note any unusual soil,geologic,topographic,cultural,weather or other conditions in "Comments"column of data sheet. Remove electrode,clean loose soil from tip,andcap.Fill hole and flag if later reoccupation is possible. ll. 12. 13. Repeat Steps 6 through 10 until survey line is completed. About once per hour,and at end of line,measure polarization between portable reference and mea - suring electrodes in copper sulfate bath. Reel in wire if possible,remove base electrode, re fill hole,and check electrode polarizationasinStep3. Equipment 1.Telluric monitor:Linear Model 142 (battery- operated,2.5 megohms input impedance),or equiv-alent single-channel recorder;up to 500 m of wire for dipole;electrodes as below. Electrodes:Tinker &Rasor Model 6B (Cu-CuS0,4) Meter:Fluke 8020A digital multimeter (10 megohms input impedance)or equivalent.Geonics SP meter of Keithley electrometer are available for high- contact-resistance situations (snow,frozen soil, etc.). Wire and reels for walking surveys:approximately 3 to 4 km of lightweight wire (typically 32 to 36 gauge)on chest reel;marked every 100 m. Auxiliary equipment:Shovel,pick,cleaning brush, splice kit,spare meter and leads,etc. vr.at SL George EXHIBIT B setton Lapoon ba Faise PassTheAleutCorporation ai Akutan &Sarak .2550 Denali ¢Suite 900 *Anchorage,Alaska99503 ce arBa,Phone (907)-274-1506 Fea -e”8 oo 3S2Veenonendlovf=|3 | March 4,1982 Mr.GeraldW.Huttrer )RECEIVED Republic Geothermal,Inc.. 11823 East Slauson Avenue MA 0 &1982 Santa Fe Springs,California 90670 Dear Mr.Huttrer: The Aleut Corporation is a regional corporation organized under the Alaska Native Claims Settlement Act (ANCSA)of 1971.The Aleut Corporation has selected the surface and subsurface rights to the | following townships,on Unalaska Island,as part of its entitlement under section 14 (h)(8)ANCSA: Township 71 South,Ranges 118 and 119 West of the Seward Meridian Township 72 South,Ranges 118 and 119 West of the Seward Meridian Township 73 South,Ranges 119 and 120 West of the Seward Meridian _ The corporation has no objection to the geothermal exploration activities on these lands,as proposed by the Alaska Power Authority and conducted by Republic Geothermal,Inc.of Santa Fe Springs,California;Dames & Moore of Anchorage,Alaska;and their associated subcontractors.However, we assume that Republic Geothermal will obtain all the necessary permits for the exploration activities and will follow appropriate engineering and environmental protection practices in their exploration.Furthermre, we expect that the exploration will be conducted with respect for the aesthetic and environmental qualities of the area:this specifically includes the mintenance of clean camps and the proper disposal of solid and liquid wastes. Sincerely, THE CORPORATION awe WENn$ Wayne F.|Lewis Land Director WFL/jh POPS JAYS.HAMMOND,GOVERNOR DEPART MENT OF FISH AND GAME 333 RASPBERRY ROAD ANCHORAGE,ALASKA 99502 March 10,1982 Dames and Moore,Inc. 800 Cordova Anchorage,Alaska 9950) Attention:Mr.Stephen Grabacki,Projet Coordinator Gentlemen: C3 Re:Unalaska Geothermal Exploratory Program The Alaska Department of Fish and Game has reviewed the Republic Geothermal, Inc.proposal to drill up to three geothermal gradient holes at Makushin Volcano near Unalaska. With respect to proximity to the area identified for drilling;the only identified anadromous fish streams are Nateekin River,Makushin Valley RiverandunnamedtributariestoHumpbackBayandMcLeesLake.All of the aforementicned streams provide spawning for pink salmon excepting the McLees Lake tributaries which provide sockeye habitat. The entire coast of Unalaska Island is utilized by marine mammals,however, the only identified area of concentration near the drilling site is the sealionhaulinggroundsatPointTebenkof(Driftwood Bay). Waterfowl and seabirds are also present throughout the entire area although there are no known colonies in the vicinity of the exploration area. Bald eagle nests have been identified at Point Tebenkof,Winslow Island artdatapointapproximatelyonemilesouthofU.S.G.S.VABM Betty (west sideUnalaskaBaybetweenCapeCheerfulandEiderPoint). With respect to protection of fish and wildlife resources,we request thefollowingprecautionarymeasuresbeobserved:"N1.Prior to diverting water from or discharging effluents from drilling operations,etc.,into and/or fording with equipment Co,Ke S.Grabacki 3/10/82 anadromous fish streams,obtain a AS 16.05.870 (statute attached)Habitat Protection Permit. 2.1500 feet separation be maintained between helicopter flight paths and active eagle nests and marine mammal concentrations. 3.Surface disturbance be minimized by consolidating drilling sites, 'emergency shelters,fuel storage areas,etc. 4,All solid and liquid wastes be transported from the site unlessonsitedisposalisapprovedbyAlaskaDepartmentofEnvironmentalConservation. Thank you for consulting us regarding this project.Please keep usrespectivetoyourcontinuingprogram. Sincerely, CobMe. Regional Su Habitat Division (907)344-0541 cc:P.Pedersen .Griffin .Calkins Arneson Fide Lechner .Daisy .RedickTrasky/K.SundbergrnoUanvaoRK informed BAMES &MOORE ANCHORAGE . DAK Ti taco ACTION OoINFO:Cc oO 0 CI Oj FILE: _ot $1.[.¥ REPUBLIC GEOTHERMAL,INC. 11823 EAST SLAUSON AVENUE SANTA FE SPRINGS,CALIFORNIA 90670 TWX .910.586.1696 (212)SAS5.366!1 QQ |A A SUMMARY OF THE UNALASKA,ALASKA GEOTHERMAL PROJECT Oy, a Introduction Unalaska is one of the Fox Islands in the central part of the Aieutian Island arc,approximately 900 miles west of Anchorage.The Aleutian Islands are part of the "Ring of Fire"that surrounds the Pacific Ocean Basin and which gets its name from the numerous active volcanoes along its trace.Mt. Makushin is a 6680-foot high active volcano situated on northern Unalaska. Makushin has erupted many times during geologically recent times,the latest. verified eruption being in 1938.It has on its flanks at least eight fumarolefields(steam vents)that evidence the continued presence of heat (geothermal energy)within the mountain. The villages of Unalaska and Dutch Harbor are located approximately 12 miles east of Makushin.The residents of both villages depend,to a great extent,on income derived from activities related to the crab and/or bottom fishing industries.These industries,in turn,depend upon the availability, on Unalaska Island,of electric power at affordable rates. Recently,because fossil fuel costs and electric power costs have been rising dramatically,new interest has been shown in assessment of the potential for economically exploiting the geothermal energy thought tc exist beneath Mt.Makushin.In 1981,the State of Alaska provided funds to the Alaska Power Authority (APA)to be used to conduct the Unalaska Geothermal Energy Project.In 1982,the APA contracted with Republic Geothermal,Inc.(Republic)to undertake the first phase of what may become the two-year feasibility study described below. The Project Phase I of the Unalaska Geothermal Project has begun with a technical planning meeting at which industry and university scientists and representa- tives of federal,state,and local entities having Unalaska experience have shared their information with Republic staff. The data thus acquired will now be used to develop a preliminary model of the geothermal resource,to assess the land ownership and environmental as- pects of the project,and to make logistical plans for 1982 field exploration. In mid-April,geologists,geochemists,geophysicists,and environmental scientists will begin work on the eastern flanks of Makushin.Geologic maps will be made;waters and gases will be sampled;the mercury and/or helium patficalaren BOLEMsStood REPUBLIC GEOTHERMAL,INC. content of soils will be analyzed;measurements will be made of the electrical fields beneath the mountain;and environmental baseline data (characterizationofthepresentenvironment)will be acquired.Republic will also be obtaining all the federal,state,and local permits required to legally undertake these and subsequent tasks. Republic plans to interpret the data acquired via these activities as quickly as possible and to begin drilling the first of three,1500-foot-deep, "thermal gradient holes"around June 1.Thermal gradient holes are used to study the geologic formations penetrated and to obtain records of subsurface temperatures.This information,when combined with geologic,geochemical, geophysical,environmental,and logistical data,will allow Republic to deter- mine the best site for a deep (4000-foot or more)geothermal test well. It is presently planned that the equipment necessary to drill the thermal gradient holes will be barged to Unalaska and then transported to the drill site by helicopter.A camp will be erected on Makushin to and from which personnel,materials,and equipment will be moved by a helicopter based at Dutch Harbor.Food and fuel will be purchased at Dutch Harbor to the greatest extent possible. In May 1983,after analyses of all data acquired in 1982,Republic plans to drill a geothermal test well as deep as possible with existing funds.If a resource is encountered,it will be tested in order to characterize and quan- tify the energy available.During all 1982 and 1983 operations,utmost atten- tion will be given to the care and preservation of the environment of Makushin and the river valleys draining the exploration areas. Economic Comparison Peak electrical power demand of the Unalaska fishing and crabbing indus- tries is currently about 15 megawatts,all of which is presently produced by diesel-fueled generators.If there proves to be as much geothermal energy on Unalaska as has been discovered in geologically similar parts of Japan,the Philippines,and Central America,then there may be the potential for produc-tion of several tens of megawatts. Preliminary economic feasibility studies suggest that the cost of 20 mega- watts of geothermally generated power would compare favorably with the cost of diesel-fueled generation when levelized over 30 years and that the costs of 30-or-more megawatts could be significantly below that of diesel fuel over the same period. Summary Statement Republic Geothermal,Inc.and the Alaska Power Authority are optimistic about the chances for discovery of geothermal resources on Unalaska.Both entities intend to conduct the project in a cost-effective,professional manner and to keep open,at all times,the lines of communication with federal,state,and especially local Unalaska observers. eaehabeOr7teBeedTaTT"thereyisSRRaewr",DeewaressowthAYae yaSaree oOPEELoeanilarea¢t.= EE an SePOPE AogFjats ace a : pee ad ee ec Seaeayee gee NRE ae pat Ba lee saeOe ra : by : Ee, ' eTONE|RE|WRT|DOROTN|GO|RTNO| OR REI AS: pian namaaSS* ue ue,he"t+FAN : - ips 4ie reer aesorsveei™ ei plait)'ar ¥ we ed mlmls eka oe aesmak i ae,on ' edt. .x OeFORRR TEN : aN we -ELtAThaodedhi3} 4 v "es z fai id ' i we pre EEE, yeRe . aa eet Bae eat, aa )Then eg Fe aera z PrTeOeele aan mthne fea' a mine aeeAll DarOO ewe EY ty R ieoAE?widen ainsa ply io gee ad 'aeYMkeBoo: ae TneianIety Kiasttuid,eal:-34i.|weg yore ae aiekswie* St x A feee? bikiwiandbe a oo TE x..'nenFEEYantsntchetim heresgeetweNaas:Be a te FreThe*x eS eet!a a a ANY .gn'hay reBhkeSg£airs Ws eg ffenwrtRe oortititieaindls cateeee,£SsUF -:aye me oeae.SEwad ¢ "% ay (aecat Miapeteer aeASeegee AMORA27ihe t' Segre:eeaan panei care wr tae AgePNdywedT.wick &aris a?i»aad .w=;os,e,_ae*eeo7,BeaexFawn!"vamtSeAD cee ee er'